brain teasers - docshare01.docshare.tipsdocshare01.docshare.tips/files/25764/257641129.pdf ·...

brain teasers It's fun to solve brain teasers and I've heard your brain is like a muscle. If you exercise it (by teasing it) you'll have a fit brain. Even if that's not true, I still like to solve them. If you know some good brain teasers, please send them to me. It can also be useful to know how to solve these for job interviews. For some reason interviewers think if you know how to solve puzzles and can think quickly you'll be an ideal employee. Have fun :

1.) By moving one of the following digits, make the equation correct. 62 - 63 = 1answer 26 - 63 = 1(26 = 2x2x2x2x2x2 = 64, ∴ 64 - 63 = 1)

2.You have a fox, a chicken and a sack of grain. You must cross a river with only one of them at atime. If you leave the fox with the chicken he will eat it; if you leave the chicken with the grain he will eat it. How can you get all three across safely?

Show the answer Take the chicken over first. Go back and bring the grain next, but instead of leaving the chicken with the grain, come back with the chicken. Leave the chicken on the first side and take the fox with you. Leave it on the other side with the grain. Finally, go back over and get the chicken andbring it over.

3.What is special about the following sequence of numbers?8 5 4 9 1 7 6 10 3 2 0The numbers are in alphabetical order.(eight, five, four, nine, one, seven, six, ten, three, two, zero)

5.)Three travelers register at a hotel and are told that their rooms will cost $10 each so they pay$30. Later the clerk realizes that he made a mistake and should have only charged them $25. He gives a bellboy $5 to return to them but the bellboy is dishonest and gives them each only $1, keeping $2 for himself. So the men actually spent $27 and the bellboy kept $2. What happened to the other dollar of the original $30?

Show the answer » LinkThere is no missing dollar from the original $30 because after getting $1 back, the three travelers had paid a total of $27 for their room ($9 each), not $30. Out of that $27, the hotel has$25 and the clerk kept the remaining $2. If you still want to work from the original $30, the travelers have $3, the hotel has $25 and the bellboy has $2. The misleading part is adding the bellboy's $2 to the $27, when in fact it should be subtracted.

6.)You are the bus driver. At your first stop, you pick up 29 people. On your second stop, 18 of those 29 people get off, and at the same time 10 new passengers arrive. At your next stop, 3 of those 10 passengers get off, and 13 new passengers come on. On your fourth stop 4 of the remaining 10 passengers get off, 6 of those new 13 passengers get off as well, then 17 new passengers get on. What is the color of the bus driver's eyes?

Show the answer The eye color of the reader of this problem. The first sentence is the key: "You are the bus driver"

7.A rooster lays an egg at the very top of a slanted roof. Which side is the egg going to roll off on?Show the answer » LinkNeither, roosters don't lay eggs.

8.)Why is it very common to have a 9 minute snooze interval on alarm clocks, why not 10 instead?Show the answer » LinkBy setting the snooze time to 9 minutes, the alarm clock only needs to watch the last digit of the time. So, if you hit snooze at 6.45, the alarm goes off again when the last digit equals 4. They couldn't make it 10 minutes, otherwise the alarm would go off right away, or it would take more circuitry.

9.A bookworm eats from the first page of an encyclopedia to the last page in a straight line. The encyclopedia consists of ten 1000-page volumes and is sitting on a bookshelf in the usual order. Not counting covers, title pages, etc., how many pages does the bookworm eat through?

Show the answer » Link __ __ B| | | |F A|1 |...........................|10|R C| | | |O K| | | |N |__| |__|T ----------------------------------

On a book shelf the first page of the first volume is on the "inside", so the bookworm eats only through the cover of the first volume, then 8 times 1000 pages of Volumes 2 - 9, then through the cover to the 1st page of Vol 10 for a total of 8,000 pages.Note: The question asks how many pages, not how many sheets of paper.

10.)An 18-wheeler is crossing a 4 kilometer bridge that can only support 10,000 kilograms and that's exactly how much the rig weighs. Halfway across the bridge a 30 gram sparrow lands on the cab, but the bridge doesn't collapse. Why not?

Show the answer » LinkSince the bridge is 4 kilometers long, the halfway point would be 2 kilometers. The 18-wheeler would have used much more than 30g of fuel to drive 2 kilometers.

11.)A completely black dog was strolling down Main street during a total blackout affecting the entire town. Not a single streetlight had been on for hours. As the dog crosses the center of the road a Buick Skylark with 2 broken headlights speeds towards it, but manages to swerve out of the way just in time. How could the driver see the dog to swerve in time?Show the answer » LinkIt was during the day

12.)In a small cabin in the woods, two men lay dead. The cabin itself is not burned, but the forest all around is burned to cinders. How did the men die?Show the answer » LinkIt's the cabin of a plane and the plane crashed.

13.)Ida puts her coffee into the microwave, as she does every morning, for exactly 2 minutes. When the microwave goes off, she opens the door, but then closes the door again and sets the microwave for 2 more seconds. What good would 2 more seconds be?

Show the answer » LinkTo rotate the handle on the mug so she can comfortably remove it.15.)You are a cook in a remote area with no clocks or other way of keeping time other than a four-minute and a seven-minute hourglass. On the stove is a pot of boiling water. Jill asks you to cook a nine-minute egg in exactly 9 minutes, and you know she is a perfectionist and can tell if you undercook or overcook the egg by even a few seconds. How can you cook the egg for exactly 9 minutes?

Show the answer » Link1. Flip both hourglasses over and drop the egg into the water.2. When the 4-minute timer runs out, flip it over (4 minutes elapsed, 3 remaining on the 7-minute timer).3. When the 7-minute timer runs out, flip it over. (7 minutes elapsed, 1 remaining in the 4-minute timer)4. When the 4-minute timer runs out, flip the 7-minute timer over. (8 minutes elapsed. 6 minutes remained in the 7-minute timer, but flipping it over leaves one minute's worth of sand on top. When it runs out exactly nine minutes will have elapsed.

I am the owner of a pet store. If I put in one canary per cage, I have one bird too many. If I put intwo canaries per cage, I have one cage too many. How many cages and canaries do I have?

Show the answer » LinkFour canaries and three cages.

66.)If you put one canary in each cage, you have an extra bird without a cage. However, if you put two canaries in each cage then you have two canaries in the first cage, two canaries in the second cage and an extra cage.

Here is a series of numbers. What is the next number in the sequence? 11121121111122131221113112221

Show the answer » LinkThe next number in the sequence is 1113213211, because the rule for creating the next numberis to simply describe the previous number. The first number is 1, or 1 (one) 1, so you get 11. To describe 11, you have two 1's, or 21. Now you have one 2 and one 1, so the next number is 1211. The solution is to simply continue describing the previous number using only numbers.

55.)My daughter has as many sisters as she has brothers. Each of her brothers has twice as many sisters as brothers. How many sons and daughters do I have?

Show the answer » LinkFour daughters and three sons. Each daughter has 3 sisters and 3 brothers, and each brother has 2 brothers and 4 sisters.99.)To figure it out mathematically, you could use the following two equations where G = the number of girls and B = the number of boys:G - 1 = B2(B - 1) = GSolving for G gives you 4 and plugging that in to G - 1 = B gives you a B of 3.

What seven-letter word has hundreds of letters in it?

Show the answer » Link

If you had a ton of feathers and a ton of stones which would be heavier?


Tom's mother has three children. One is named April, one is named May. What is the third one named?

Show the answer » LinkTom

Two women apply for a job. They are identical and have the same mother, father and birthday. The interviewer asks, "Are you twins?" to which they honestly reply, "No".

How is this possible?

Show the answer » LinkThey are triplets.

You are standing outside a closed door. On the other side of the door is a room that has three light bulbs in it. The room is completely sealed off from the outside. It has no windows and nothing can get in or out except through the door. On the outside of the room there are three light switches that control each of the respective light bulbs on the other side of the door.

Your assignment is to determine which light switch controls which light bulb. You are allowed to enter the room only once, and once you come out, you must be able to state with 100% certainty which light switch controls which light bulb.

Show the answer » LinkTurn one light switch on, wait a few minutes, then turn it off and turn another light switch on. Go into the room and feel the light bulbs. The one that's still warm is connected to the switch that you first turned on, the one that is on was the second switch you turned on, and the last bulb is controlled by the switch that you didn't touch.

If a bottle and a cork cost a dollar and a nickel, and the bottle costs a dollar more than the cork, how much does the cork cost?

Show the answer » LinkMost people guess 5¢, but $1 more than 5¢ is $1.05, and if the bottle cost $1.05, the bottle and the cork would be $1.10, not $1.05. The cork actually costs 2½¢ and the bottle costs a dollar more, or $1 and 2½¢, making the total $1.05.

A boat has a ladder that has six rungs. Each rung is one foot apart. The bottom rung is one foot from the water. The tide rises at 12 inches every 15 minutes. High tide peaks in one hour.

When the tide is at its highest, how many rungs are under water?

Show the answer » LinkNone. The boat is floating on the water, so as the tide rises, so does the ladder.

You have a lighter and two fuses that take exactly one hour to burn, but they don't burn at a steady rate. For example, one fuse could take 59 minutes to burn the first inch and then burn the rest of the fuse in the last minute.

How would you use these two fuses to measure 45 minutes?

Show the answer » LinkLight the first fuse on both ends and the second fuse at only one end. When the first fuse burns out you know 30 minutes have passed. Light the other end of the second fuse and when it burnsout, 45 minutes have passed.

You have two buckets - one holds exactly 5 gallons and the other 3 gallons. How can you measure 4 gallons of water into the 5 gallon bucket?

(Assume you have an unlimited supply of water and that there are no measurement markings ofany kind on the buckets.)

Show the answer » LinkFill the 3-gallon bucket.Pour the 3 gallons of water into the 5-gallon bucketFill the 3-gallon bucket again.Fill up the 5-gallon bucket with the 3-gallon bucket, leaving you with 1 gallon left in the 3-gallon bucket.Empty out the 5-gallon bucket.Pour the remaining 1 gallon of water from the 3-gallon bucket into the 5-gallon bucket.Fill the 3-gallon bucket.Pour the 3 gallons of water from the 3-gallon bucket into the 5-gallon bucket leaving you with 4 gallons of water in the 5-gallon bucket.

Alternate solution:Fill up the 5 gallon bucketPour it into 3 gallon bucket, leaving 2 gallonsEmpty out the 3 gallon bucketPour the 2 gallons in the 5 gallon bucket into the 3 gallon bucketFill up the 5 gallon bucket and pour it into the 3 gallon bucket until it's full, leaving 4 gallons in the 5 gallon bucket.

A princess is as old as the prince will be when the princess is twice the age that the prince was when the princess's age was half the sum of their present ages.

What are their ages?

Show the answer » LinkThis one took a while, but I figured it out. You can find the answer here.

During WWII, there was a bridge connecting Germany and Switzerland, and on the German side,there was a sentry tower with a guard in it. He would come out every three minutes to check on the bridge, and he had orders to turn back anyone who tried to get into Germany, and shoot anyone trying to escape without a pass. There was a woman who desperately needed to get intoSwitzerland, and she knew she didn't have time to get a pass. It would take her at least six minutes to cross the bridge, but she managed to do it. How?

Show the answer » LinkShe walked on the bridge towards Switzerland for 3 minutes and just as the guard was about to come out, she turned around walking back to Germany. The guard saw her and asked for her pass but she didn't have one and was sent back (or what the guard thought was back) to Switzerland. In her case it was the very country she wanted to go to.

A man can make perfect counterfeit bills. They look exactly like real ones, they're made of exactly the same materials, made the same way, everything. So perfect, one could pretty much call them real bills. One day he successfully makes a perfect copy of another bill. However, he gets caught when he tries to use the copy. How is this possible?

Show the answer » LinkHe made a perfect copy of a counterfeit bill.

A prisoner is told "If you tell a lie we will hang you; if you tell the truth we will shoot you." What can he say to save himself?

Show the answer » LinkYou will hang me. If they hang him, then the statement was true and they could only hang him for telling a lie. If they shoot him, then it makes the statement a lie and they were only to shoot him for telling the truth. An alternate solution is to say, "You will not shoot me," leading to the same quandary for the killers.

How many people can read hex if only you and dead people can read hex?


A man is traveling with a fox and two chickens, if he leaves the fox alone with the chickens the fox will eat the chickens. He comes to a river and needs to cross it, he finds a small boat that can carry only him and one animal, how does he get himself, the fox and two chickens across the river safely?

Show the answer » LinkTake the fox over, return with nothing. Go over with one chicken, return with the fox. Go over with the second chicken, return with nothing. Finally, take the fox over.

A man is looking at a picture of a man on the wall and states: Brothers and sisters I have none, but this man's father is my father's son. Who is the man in the picture in relation to the man looking at the picture?

Show the answer » LinkThe man in the picture is his son. Since he doesn't have any brothers or sisters, the statement my father's son is himself. A shortened version would be this man's father is myself, so he is the father of the man in the picture.

A man and his son had a terrible car accident and were rushed to the hospital. The man died on the way, but the son was still barely alive. When they arrived, an old gray surgeon was called in to operate. Upon seeing the young boy, the surgeon said, "I can't operate - this is my son."How is this possible?


A wise king devised a contest to see who would receive the Princess' hand in marriage. The Princess was put in a 50 x 50 foot carpeted room. Each of her four suitors were put in one cornerof the room with a small box to stand on. The first one to touch the Princess' hand would be the winner and become the new King.

The rules were the contestants could not walk over the carpet, cross the plane of the carpet, or hang from anything; nor could they use anything but their body and wits (i.e. no magic, telepathy, nor any items such as ladders, block and tackles etc). One suitor figured out a way and married the Princess and became the new King. What did he do?

Show the answer » LinkAsked the princess to touch his hand.

Two guards were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?"

How did he know his companion was smiling?

Show the answer » LinkThey were facing each other. As to why his companion was smiling, the world may never know.

You're riding a horse. To the right of you is a cliff and in front of you is an elephant moving at thesame pace and you can't overtake it. To the left of you is a hippo running at the same speed anda lion is chasing you. How do you get to safety?

Show the answer » LinkGet off the merry-go-round.

You have 50 quarters on the table in front of you. You are blindfolded and cannot discern whether a coin is heads up or tails up by feeling it. You are told that x coins are heads up, where 0 < x < 50. You are asked to separate the coins into two piles in such a way that the number of heads up coins in both piles is the same at the end. You may flip any coin over as many times asyou want. How will you do it?

Show the answer » LinkTake x coins, flip all of them and put them in one pile. The rest of the coins form the second pile.

You have four chains. Each chain has three links in it. Although it is difficult to cut the links, you wish to make a single loop with all 12 links. What is the fewest number of cuts you must make to accomplish this task?

Show the answer » Link3 cuts. Cut each link in one chain. Separate them, and use the links to join the ends of the 3 intact chains.

Walking down the street one day, I met a woman strolling with her daughter. "What a lovely child," I remarked. "In fact, I have two children," she replied. What is the probability that both of her children are girls?

Show the answer » Link1/2 probability. There was a raging debate on this brain teaser, which I got from 3quarksdaily, and after many comments, the conclusion was that the problem is stated poorly, but there is a 1/2 probability that both of her children are girls.

Three closed boxes have either white marbles, black marbles or both, and they are labeled white, black and both. However, you're told that each of the labels are wrong. You may reach into one of the boxes and pull out only one marble. Which box should you remove a marble fromto determine the contents of all three boxes?

Show the answer » LinkThe one labeled both. Since you know it's labeled incorrectly, it must have all black marbles or all white marbles. After you determine what it contains, you can identify the other two boxes by the process of elimination.

A glass of water with a single ice cube sits on a table. When the ice has completely melted, will the level of the water have increased, decreased or remain unchanged?

Show the answer » LinkThe water level remains unchanged because the ice cube displaces its own weight. If you're not convinced, read Archimedes' Principle, which states that any floating object displaces its own weight of fluid. Still not convinced? Here are a few more sources .

You are given eight coins and told that one of them is counterfeit. The counterfeit one is slightly heavier than the other seven. Otherwise, the coins look identical. Using a simple balance scale, how can you determine which coin is counterfeit using the scale only twice?

Show the answer » LinkFirst weigh three coins against three others. If the weights are equal, weigh the remaining two against each other. The heavier one is the counterfeit. If one of the groups of three is heavier, weigh two of those coins against each other. If one is heavier, it's the counterfeit. If they're equal weight, the third coin is the counterfeit.

I was visiting a friend one evening and remembered that he had three daughters. I asked him how old they were. "The product of their ages is 72," he answered. Quizzically, I asked, "Is there anything else you can tell me?" "Yes," he replied, "the sum of their ages is equal to the number of my house." I stepped outside to see what the house number was. Upon returning inside, I saidto my host, "I'm sorry, but I still can't figure out their ages." He responded apologetically, "I'm sorry, I forgot to mention that my oldest daughter likes strawberry shortcake." With this information, I was able to determine all three of their ages. How old is each daughter?


You're in a room with two doors. There's a guard at each door. One door is the exit, but behind the other door is something that will kill you. You're told that one guard always tells the truth and the other guard always lies. You don't know which guard is which. You are allowed to ask one question to either of the guards to determine which door is the exit. What question should you ask?


How far can a dog run into the forest?


What number comes next?2, 2, 4, 12, 48, ___


You are a prisoner sentenced to death. The Emperor offers you a chance to live by playing a simple game. He gives you 50 black marbles, 50 white marbles and 2 empty bowls and instructsyou to divide the 100 marbles into the two bowls. You can divide them however you want as long as all the marbles are in the bowls. You will be blindfolded and the bowls and marbles will be throughly mixed. You will then choose a single marble from one of the bowls. If the marble is white, you live. Black and you will be put to death.

How do you divide the marbles up so that you have the greatest probability of choosing a white marble?


What is the next number in this series?1, 2, 6, 42, 1806?


If:2 3 = 107 2 = 636 5 = 668 4 = 969 7 = ??


What do the following numerals represent?11111121113122223222


You must buy 100 chickens for exactly $100, and purchase at least one chicken from each store.The first store charges 5 cents/chicken, the second charges $1/chicken and the third charges $5/chicken. How many chickens should you buy from each store?


What is special about the following number sequence?8, 5, 4, 9, 1, 7, 6, 10, 3, 2, 0


Which two numbers are missing and where do they go in the sequence?8, 11, 5, 14, 1, 7, 6, 10, 13, 3, 12, 2


What 4-digit number abcd satisfies this equation?4 * abcd = dcba


Bill buys three items at the store for exactly $100. The second item costs half as much as the first item, and the third item is half as much as the second. How much did each one cost?


A man was killed on Sunday morning. His wife found the body and called the police. The police arrived and questioned the chef, maid, butler, and gardener. Their alibis were:Chef - making breakfastMaid - getting mailButler - setting tableGardener - watering plantsThe police immediately arrested the criminal. Who was it and how did they know?


This is an unusual paragraph. I'm curious as to just how quickly you can find out what is so unusual about it. It looks so ordinary and plain that you would think nothing was wrong with it. In fact, nothing is wrong with it! It is highly unusual though. Study it and think about it, but you still may not find anything odd. But if you work at it a bit, you might find out. Try to do so without any coaching.


A murderer is condemned to death. He has to choose between three rooms. The first is full of raging fires, the second is full of assassins with loaded guns, and the third is full of lions that haven't eaten in 3 years. Which room is safest for him?


Name three consecutive days without using the words Wednesday, Friday, or Sunday.


A plane crashed on the border or US and Canada. Where do they bury the survivors?


There are six glasses in a row. The first three are full of water, and the next three are empty. By moving only one glass how can you make them alternate between full and empty?


What four weights can be used to balance from 1 to 30 pounds?


Given these equations, what is the answer to the last one?5 3 2 = 1510129 2 4 = 1836628 6 3 = 4824665 4 5 = 2025047 2 5 = ?


Three numbers, 16, 14 and 38, need to be assigned to one of the rows of numbers below. Wheredo the numbers belong? (Hint: This is not a mathematical problem. The numerical values are irrelevant)

A 0 6 8 9 3B 15 27 21 10 19C 7 1 47 11 17Show the answer » Link

44 33 555 555 666 9 666 777 555 3What is the message in this code?


Two men are standing on one side of a bridge and two women are approaching them. One of themen says, "Here comes my wife and daughter" to which the second man replies, "Here comes my wife and daughter". If they have not married the same woman and the women aren't pregnant, how is this true?


Rearrange the letters in the words "new door" to make one word.


Two fathers and two sons go fishing together in the same boat. They all catch a fish but the totalcatch for the day is 3 fish. How is this possible?


A green glass door admits only certain objects. Apples and balls are allowed, but pears and bats aren't. What determines whether an item can enter?


B,C,D,E,G,PWhat is the next letter in the sequence?


A mile-long train is moving at sixty miles an hour when it reaches a mile-long tunnel. How long does it take the entire train to pass through the tunnel?


Stands-----------0_2345

What does this represent?


First, think of the color of clouds. Next think of the color of snow. Last, think of the color of the moon. Now, what do cows drink?


Rhonda will go see ballet but not the opera. Her favorite number is eight and she doesn't like nine. She likes salmon but not trout. She hates Mondays and likes Wednesdays. Does she use a comb or a brush?


On a regular 12-hour digital clock how many times would the same three digits in a row be displayed (e.g. 1:11, 11:12, 12:22) in one day?


A man says his dog can jump over his house. No one believes him but he is right. How is that possible?


Five pigeons are sitting on a fence. The farmer comes out and shoots one. How many are left?


A plane with 50 passengers crashes and everyone is killed, but there were only 49 bodies. How is this possible?


A man leaves home, turns left, goes straight, turns left again, goes straight and turns left once more then returns home and there's another man with a mask on. What's going on?


A man is leaving on a business trip and stops by his office on the way to the airport. The night watchman stops him and says, "Sir, don't take that flight. I had a dream last night that your plane would crash and everyone would die!" The business man cancels his trip and sure enough,the plane crashes, killing all the passengers. The man gives his watchman a $10,000 reward for saving his life, then fires him. Why?


If you were to spell out the numbers, how far would you have to go before encountering the letter 'A'?


A sharpshooter hangs up his hat, turns around and walks 50 meters, then turns around and shoots his gun, putting a hole right through his hat. How did he do it?


5 cats can catch 5 mice in 5 minutes. How many cats does it take to catch 100 mice in 100 minutes?


You are in a room with no windows, doors or any exit. The only items are a mirror and a table. How do you escape? (Not a typical brain teaser)


There's a green ranch house on a green street with green walls, tables and chairs. What color is the staircase?


A man saw a snake crossing the road and swerved to crush it with his tires. All the street lights were off as well as the car's headlights. There were no other lights on along the road. How did the man see the snake?


Four cards are placed in front of you on the table, each with a number on one side and a color on the other. The visible cards show 3, 8, red and brown. Which cards should you turn over in order to test the truth of the statement that if a card shows an even number on one face, then its opposite face is red?

3 8 Red BrownShow the answer » Link

What do the following words have in common?current, by, dew, faze, loan, ate


How can you alter the following equation by a single stroke to make it correct?5 + 5 + 5 = 550


During lunch hour a group of boys from Mr. Bryant's homeroom visited a nearby grocery store. One of the five took an apple.

Jim said, "It was Hank or Tom".Hank said, "Neither Eddie nor I did it."Tom said, "Both of you are lying."Don said, "No, one of them is lying, the other is speaking the truth."Eddie said, "No, Don, that is not true."When Mr. Bryant was consulted, he said, "Three of these boys are always truthful but two will lie every time."Who took the apple?


A six-digit number represented by ABCDEF (each letter represents a different number) can be multiplied by 2, 3, 4, 5, and 6 and yet no new digits appear in the result. As a matter of fact, all the digits are rotated. What is the number?


What do these represent?

24 = HiaD26 = LotA7 = DotW9 = LoaC 12 = SotZ88 = PK


How do you pronounce Ghoti?


What does this sentence represent?

Stand Take Mine Taking I You To MyShow the answer » Link

What is the only anagram of Springiest?


How do you get from cold to warm in four steps, changing only one letter at a time?


How do you turn 2 into 5?


What is N?6, 9, 27, 54, N, 2241


Two boys weighing 50 pounds each and their older brother weighing 100 pounds wish to cross a river. Their boat will only hold 100 pounds. How can they all cross the river in the boat?


A circular island with a diameter of 30 feet has a 30 foot tree stands at the center. A man cuts the tree down with his chainsaw, making the cut a foot up from the ground. The tree comes crashing down and hits the water but doesn't splash. Why not?


What word or expression does this represent?ABCDEFGHIJKLMNOPQRSTVWXYZ


Jack is looking at Anne, but Anne is looking at George. Jack is married, but George is not. Is a married person looking at an unmarried person?A) YesB) NoC) Cannot be determined


What is the missing number?2 3 4 15 123 4 5 28 204 5 6 45 305 6 7 66 426 7 8 ?? 56


Two scruffy dogs were walking down the street. The first dog turned to the other and said, "Do you realize that if one of your fleas jumped onto me we would have the same number of fleas?" The second replied, "Yes, but if one of your fleas jumped onto me I would have five times as many fleas as you." How many fleas are on each dog to begin with?


A snail creeps 10 feet up a wall during the daytime, then falls asleep. It wakes up the next morning and discovers it slipped down 6 feet. If this happens each day, how many days will it take to reach the top of a 22 foot wall?


Two children were playing checkers and each played five games. Both children won the same number of games yet there were no ties. How is this possible?


How can you put 21 pigs in 4 pigpens and still have an odd number of pigs in each pen?


A woman gave a man a list of things she needed to buy at the store. The man gave the list back to the woman and she turned red with embarrassment. Why?


Mike, Jimmy, Nader, Kevin, and Larry were the top five finishers in the regional 500-mile race. They drove yellow, orange, green, red and blue cars but not necessarily in that order. Neither Kevin nor Larry drove the green car. Kevin finished faster than Mike and Larry. The blue car finished earlier than Larry's and Nader's car. The yellow car finished faster than the green car and the orange car. Mike's and Larry's car finished ahead of the orange car. Jimmy's car finished before the blue and the yellow car. Who drove what color car and what place did each driver finish?


While driving his car a man slams on the brakes when he sees, in the middle of the street, a diamond studded door, a gold door and a silver door. Which door does he open first?


Ronald has a rare opportunity to meet the President of the United States. During his visit the president gives him a gift but tells Ronald he is never to sell it unless he sees the president again. Ronald consents, but the president dies later that year. Years later a man offers to buy the President's gift for $1000. Ronald agrees and exchanges the gift for 20 crisp $50 bills. Did hekeep his promise?


What 3 digit number has a tens digit that is 5 more than the ones digit and a hundreds digit thatis 8 less than the tens digit?


Why are manhole covers round?


You are in the woods with owls and wolves. There are 22 eyes and 32 legs. How many owls and wolves are there?


When can ten plus ten equal ten, yet ten minus ten equal twenty?


Eat flush to my nose tree times for they buy dead by too. What is the answer?


A man owed his friend $63 and repaid him the exact amount in cash without using coins or $1 bills (no online transfers, checks, credit cards or any other tricks) and without requiring change. How did he do it?


Fill in the blanks with the same 4 letters to make 5 different words.

A ____ old woman on ____ bent, picked up her ____ and away she went. “____ my son” she was heard to say, “what shall we do to ____ today?”


Perform this calculation in your head, mentally adding the numbers as quickly as you can. Start with 1000 and add 40. Now add 1000. Add 30 to that, then add another 1000. Now add 20 to that result. Add another 1000 and finally, add 10 to that. What is the total?


Read this sentence.

Finished files are the result of years of scientif- ic study combined with the experience of years.

How many times does the letter F appear?


Without changing the order of these numbers, how can they equal 100?3 5 6 2 54 5


A taxi driver runs through four red lights, two stop signs and goes through a house. A police officer witnesses this but doesn't do anything. Why not?


Suppose you have twelve eggs and a balance scale. All of the eggs are identical except for one whose only difference is its weight. Using the scale only three times, determine which egg is theodd egg out and whether it is heavier or lighter than the other eggs.


What number belongs at the beginning of this sequence??, 3, 2, 3, 9, 2, 4, 8, 4, 3, 7, 6


Imagine you're alone in a boat with a large hole in the bottom. Sharks are swimming around youon all sides and the boat is sinking fast. How do you survive?


A clock loses exactly ten minutes every hour. If the clock is set correctly at noon, what is the correct time when the clock reads 3:00pm?


A man is running across a field at night clutching something in his arms as several other men pursue him. He looks back and sees they're getting closer. In a final burst of effort his pursuers catch up and bring him crashing to the ground. His pursuers stand over him but do not touch him or take what he was carrying. Why not? Who was the running man?


Two cowboys live next door to each other and both have a corral for their cows in the back. One day they meet at the back of their homes, standing next to a wall dividing their corrals. The first cowboy gets to thinking and asks his neighbor for a cow so he can double his herd. The other cowboys replies, "That's fine by me partner, cuz then we'll have the same number of cows?" How many cows does each cowboy own?


On a dark, stormy Halloween night, four kids named Luke, John, Sarah and Bob walk into a haunted house during a blackout. Only one can escape. They take a staircase to the second floor, a trapdoor on the left, then go up the ladder to the right, followed by a 28-foot slide to the basement through the mouth of a Giant Panda. In one corner of the murky cellar is a chainsaw, a dagger, a rope with a noose and an electric chair. Written on the wall in blood are the words, "Only one will survive - choose your death!" Bob takes the rope, Sarah picks up the dagger, Johnchooses the chainsaw and Luke uses the chair.Who survives?


What does this represent?Pot OOOOOOOO


Given the numbers 1, 6, 7 and 9, find an equation that equals 24. You may only use each digit once.


O, S, C, Y, S, B, T, D, ?What is the next letter in the sequence?


A red-house is made of red bricks, has a red wooden door and a red roof. A yellow-house is made of yellow bricks, has a yellow wooden door and a yellow roof. What is a green-house madeof?


On a game show there are three closed doors - one hides a car and the other two conceal a goat. The contestant selects a door, which remains closed, and the host, knowing where the car is hidden, reveals a goat behind one of the remaining two doors. The contestant is then given the option to switch doors or stay with the one they originally selected. What should the contestant do to have the best chance of winning the car?


If a plane sits on a conveyer belt whose speed matches that of the plane in the opposite direction, can the plane take off?


Go back. You must strive to find a way to stay alive. What is 4+no.5?


What 6-letter word has the same pair of letters in spots 1 and 5, a different pair in spots 2 and 6 and contains a 'u' in between?


What letter comes next?O T T F F S S


SO, ND, JF, MA, __, __

What are the next two pairs of letters?


Three rooms contain, 1) Gold coins, 2) Currency notes and 3) Cotton bags. If all three rooms catch fire, which room will the ambulance pour water on first?


Alfred and Bill are clerks at the local grocery store. Alfred can stock a shelf in 20 minutes, but Bill is new and takes 30 minutes. How long would it take for them to stock a shelf together?


Ralph goes to the hardware store to buy something for his house. He asks the clerk how much one will cost and the clerk looks it up and tells him it will be $3. He asks about buying twelve and is told it will be $6. Two hundred will cost $9. What is Ralph buying?


Your are given the numbers 777, 888 and 999. Using the numbers once and adding, subtracting,multiplying or dividing, how can you make 999?


This problem can be solved by pre-school children in five to ten minutes, by programmers in an hour and by people with higher education...well, check it yourself.

8809 = 67111 = 02172 = 06666 = 41111 = 03213 = 07662 = 29313 = 10000 = 42222 = 03333 = 05555 = 08193 = 38096 = 51012 = 17777 = 09999 = 47756 = 16855 = 39881 = 55531 = 02581 = ?

Show the answer » Link2. The number of closed circles in the 4 digits. 0, 6 and 9 each have one, 8 has 2.

A boat full of people goes under a bridge and when it comes out the other side not a single person is on it. How can this be?

Show the answer » LinkAll the passengers are married.

Jim and Wanda both have some apples. If Jim gives Wanda an apple, they will both have the same number of apples. However, if Wanda gives Jim an apple, Jim will have twice as many as Wanda. How many apples do Jim and Wanda each have?

Show the answer » LinkJim has 7 apples and Wanda has 5 apples.

He was the perfect gentleman even though his nephew couldn't see it. Who was he?

Show the answer » LinkA fine chap with a blind nephew (or an exemplary uncle who died before his nephew was born).

From a basket of mangoes when counted in twos there was one extra,counted in threes there were two extra,counted in fours there were three extra,counted in fives there were four extra,counted in sixes there were five extra,but counted in sevens there were no extras.At least how many mangoes were there in the basket?

Show the answer » Link119. The number has to be evenly divisible by seven for there to be no extras when counting in sevens, and it has to be odd in order for there to be one extra when counting by twos. It also can't be evenly divisible by three through six. 119 is the first odd multiple of 7 that satisfies the requirements.

gges egsg segg esggWhat does this represent?

Show the answer » LinkScrambled eggs

A man without eyes saw plums on a tree,He didn't take plums nor plums did he leave.How can this be?


What word can be written forward, backward or upside down while still remaining the same word?


Two days ago Lilly was 7 years old. Next year she will turn 10. How can this be?


How can you cross out four letters from the word LIVING to leave six remaining?


011 235 813 213 ???What comes next?


A women and daughter walked into a restaurant. A man walked past and the women both said, "Hello, Father". How is this possible?


When Randolph asked Hilda how old she was, Hilda replied that in two years she would be twice as old as she was five years ago. How old is Hilda?


The 17 items in your shopping cart weigh 8 pounds. But when your daughter puts in a ball, poster board and yo-yo the shopping cart weighs less. How is that possible?


A mother of three children had six apples. She gave two to each and yet 4 remained. How was this possible?

Show the answer » LinkShe gave the same 2 apples to each child in succession.

A dad offered to pay his son $5 for every correct answer on his math test. His son said he would pay his Dad $8 for every incorrect answer. There were 26 questions on the test and no money was exchanged. How?

Show the answer » LinkThe son got 16 questions correct and missed 10. This means he owed his Dad 10 * $8 = $80, but his Dad owed him 16 * $5 = $80, so it was a wash.Two math equations to solve it are x + y = 26 and 5x = 8y.

If two hours ago it was as long after one o'clock in the afternoon as it was before one o'clock in the morning, what time is it right now?

Show the answer » Link9pm (or 21:00). There are 12 hours between 1pm and 1am, so 6 hours after 1am is halfway. 6 hours + 1pm equals 7pm. In order for 7pm to be 2 hours behind the current time, it must be 9pm.

A man walks out of a house that has four walls all facing north. A bird walks past him. What kindis it?

Show the answer » LinkA penguin. If all four walls face north the house must be at the southernmost point of the earth. Really, any native antarctic bird would work.

This brain teaser is quite similar to the guy whose house walls face south and sees a bear, then you're asked the color of the bear. The bear would be white (a polar bear) as they're the only bears indigenous to the north pole. A lawyer would claim it's all circumstantial evidence and the bear could be an imported brown bear. The laywer makes a valid point.

What is the longest word in the English dictionary?

Show the answer » LinkSmiles because there is a mile between the two s's. (Groan)

What is special about the phrase, 'Race car'?

Show the answer » LinkIt's a palindrome (a word or phrase that's spelled the same backwards and forwards).

A man gets off the bus looking for an address and approaches a couple walking in the same direction for directions. The woman says they're going that way and take him. Along the way theman asks if they're related. The woman grins and says, "We're not strangers. This man's mother is my mother's mother-in-law." The man is confused but doesn't say anything. When he gets back home he tells his wife about the conversation and she can't figure it out either. They decide to ask their lawyer and he eventually works it out with pen and paper. How are the couple related?

Show the answer » LinkThe couple is either a man and his daughter or an uncle and his niece.

A dad told his son he would give him $5 for every correct answer on his math test. His son replied that he would pay $8 for every incorrect answer. There were 26 questions on the test and no money was exchanged. Why?

Show the answer » LinkThe son answered 16 questions correctly, missing 10. He owed his Dad 10 * $8 = $80 but his Dad owed him 16 * $5 = $80, so they were even.

How do you get 24 from 9, 6, 11 and 3 using addition, subtraction, multiplication or division?

Show the answer » Link(6 - 3) x 11 - 9

Phil asks his friend Stan when his birthday is. Stan replies that he was 32 the day before yesterday and next year he'll be 35. When is his birthday and how is this possible?

Show the answer » LinkToday is Jan 1st and his birthday is on December 31st. He was 32, then turned 33 on Dec 31st, and this year on Dec 31st he'll turn 34, so next year he'll be 35.

A man wants to get into a night club where the bouncers test each person before they can enter.The man waits and watches. A woman walks up to the bouncers and the bouncers say 6. The woman replies with 3 and goes in. A small man walks up and they say 12. The man replies 6 andis admitted. The first guy thinks he's figured it out and walks up. They say 4 and the man replieswith 2, but they don't let him in. What should he have said?

Show the answer » Link4. The answer is the number of letters in the number. Six has 3 letters, twelve has 6 letters and four has 4 letters.

What is half of 8? (Hint: It's not 4)

Show the answer » Link3 (if you slice vertically) or o (if you slice horizontally)

Using all the digits from 1 to 7, what two numbers have the largest product? For example, 1234 x 567 = 699678 but you can do much better than that.

Show the answer » Link742 x 6531 = 4,846,002.

A similar problem can be found in L.A. Graham's Ingenious Mathematical Problems and Methods with a range of 1 to 9, but the principle remains the same - the numbers with the smallest difference produce the largest product. You start out with the highest two digits, 7 and 6, then attach 5 and 4, putting the smaller of the two digits with the larger number, giving you 74 and 65. The next two highest digits are 3 and 2, giving you 742 and 653. Finally, you add the 1 to the lower number. Page 80 has the details of that solution.

I have nine matchbox sticks and would like to make ten. How do I do it?

Show the answer » LinkArrange the nine matchbox sticks like so to make the shape of the number ten: _ /| | | | |_|

In 2012 a class was divided into 2 groups. Their assignment was to find the names of at least 3 children who were born on the same day from 5 different months of 2011. These were the results:

Group 1August 20: Oliver, William, and Adam.January 3: John, Alice, and Ken.September 7: Bruce, Shane, and Peter.

June 11: April, Patrick, and Bobby.July 19: Trent, Julie, and Charles.

Group 2March 1: Karl, Willie, and Patty.February 29: Blake, Kobe, and Wayne.December 24: Kyle, Chad, and Zoe.May 12: Matthew, Manny, and Adrian.November 20: Greg, Fiona, and Elizabeth.

The members of group 2 got an F on the assignment. Why?

Show the answer » LinkGroup 2 failed because 2011 wasn't a leap year, meaning there was no February 29th.

If you and a friend have the same amount of apples, how many does she need to give you in order to have 10 more apples than her?

Show the answer » LinkShe will always need to give you 5 apples. You both need at least 5 apples to begin with, but apart from that it doesn't matter exactly how many you each have. When she gives you 5 you will have 10 more than her because she will lose 5 and you will gain 5, resulting in a net difference of 10.

For example, if you each have 25 apples and she gives you 5 of hers, she will be left with 20 andyou will now have 30, precisely 10 more than she has.

What do the following words have in common?

far, blow, bacon, lather, fasting, wariness, pacemaker

Show the answer » LinkEach of these words becomes a new word when the letter 'e' is placed after the first letter.

fear, below, beacon, leather, feasting, weariness, peacemaker.

How can you write a date in 5 letters without using any numbers?

Show the answer » LinkThe most popular answer for this teaser is 'today'. Of course this only works if you're reading it on that particular date or if the date is not specified. Another option is to respond literally with 'adate'. Lastly, certain dates could be squeezed into letters using Roman numerals if you abbreviate the year to 2 numerals. For example, January 20th, 2011 would be I XX XI.

How can the numbers 6, 1, 7 and 9 be arranged to make 24?

Show the answer » Link(9 - 6) × (1 + 7) = 3 × 8 = 24

How many of each animal did Moses take on the ark?

Show the answer » LinkNone. Moses didn't have an ark, Noah did (and yes, he took 2 of each animal).

How is 7 different from the rest of the numbers from 1-10?

Show the answer » Link7 (seven) is the only one with two syllables.

There are six men carrying a box holding six cats and each cat has 6 kittens. How many legs arethere in total?

Show the answer » Link1020. There are 6 men with 2 legs each, for a total of 12 legs.There are 36 cats with 4 legs each for a total of 144 legs.There are 216 kittens with 4 legs each for a total of 864 legs12 + 144 + 864 = 1020.

Three ants are walking in the same direction. The first ant has two ants behind him, the second ant has one in front and one behind, but the third ant has one in front and one behind too. How is this possible?

Show the answer » LinkThe ants are in a circle. Lets say the ants are A, B and C. A has has B and C behind him, B has A in front and C behind, and C has B in front and A behind.

What does this represent? BAN ANA

Show the answer » LinkBanana split. It's the word banana, and it's split apart.

What is this phrase? XQQQME

Show the answer » LinkExcuse me. Literally, x + q's + me.

You are a spy and need to send an item to a contact in another country without letting anyone else have access to it. All unlocked items will be opened in transit. How can you send this item securely?

Show the answer » LinkPlace a lock on the item and send it to your contact. They will place their own lock on the package and return it to you. You remove your lock and send it back. When they receive it, they can unlock the package and retrieve the item.

What does this represent?chimadena

Show the answer » LinkMade in china. The word "made" is wedged between the word "china" (chi-na)

What does this represent?esroh gnidir

Show the answer » LinkHorse back riding. The words are horse and riding spelled backwards.

How much dirt is there in a hole that measures two feet by three feet by four feet?

Show the answer » LinkNone. A hole doesn't have any dirt.

The defendant testified, "The attorney is my brother," but the attorney took the stand and denied having a brother under oath. Who is lying?

Show the answer » LinkNeither one of them lied. The defendant was the attorney's sister.

How could the 22nd and the 24th U.S. Presidents have the same parents, but not be brothers?

Show the answer » LinkThe 22nd and 24th U.S. presidents were both the same person - Grover Cleveland.

Dina comes from a large family and has over 20 cousins. How is it possible that all of her cousins have an aunt who is not her aunt?

Show the answer » LinkThe aunt of all of her cousins is Dina's own mother.

A zebra was going to the river. On the way the zebra encountered five giraffes. Each giraffe had five monkeys on their neck. How many animals were going to the river?

Show the answer » LinkJust one - the zebra. The other 30 animals (5 giraffes and 25 monkeys) were going the other way.

What is the only word in the English dictionary that has a silent z?

Show the answer » LinkThe word rendezvous. Even though it's a French word, it's in the English dictionary and is pronouced [rahn-duh-voo].

James makes a bet with Laura that he can use any name she can think of in a song she will recognize with the original lyrics. Laura takes him up on the bet and loses. What song did James sing to win?

Show the answer » LinkHappy Birthday. When you sing Happy Birthday, you say the person's name as part of the song.

What is a six-word sentence that has the same meaning and spelling in both English and Afrikaans?

Show the answer » LinkMy pen is in my hand. It's not all that meaningful of a sentence, but it's the same in English and Afrikaans.

What do these words have in common?1. Banana2. Dresser3. Grammar4. Potato5. Revive6. Uneven7. Assess

Show the answer » LinkIf you move the first letter to the end of the word, it forms the same word backwards. Banana = ananab, dresser = resserd, and so on.

What phrase do these words sound like when rearranged?amid eerie niger won spawn

Show the answer » Link"Won spawn amid niger eerie" sounds like, "Once upon a midnight dreary", from The Raven by Edgar Allan Poe.

At the market you can buy a cow for $10, a pig for $1 and 8 hens for $1. How many animals would you need to buy to get 100 mixed animals for exactly $100?


7 cows, 21 pigs and 72 hens. The trick to this is finding the combination of cows and hens with the same cost and quantity since pigs are already equal. The magic combination is 7 cows and 72 hens, giving you 79 animals that cost $79 ($70 + $9). Then you just add 21 pigs to get to 100 animals.

A man goes to bed at 9:45 pm. He makes himself a drink, then turns off the TV and the lights. The night was windy and there was a major storm. The next day he discovers he was the cause of seven deaths. How is this possible?

Show the answer » LinkHe lived in a lighthouse as lighthouse keeper. He turned off all the lights by accident, so a ship with 7 passengers couldn't negotate the rocky shores. One would think the light switches in a lighthouse would be more clearly marked.

An electric train is traveling on a 2000-mile journey from Chicago, IL to Los Angeles, CA. It has 16 cars with a total of 320 passengers. The weather is cloudy and cool, with a warm front approaching from the south. Which direction will the steam blow?

Show the answer » LinkThere is no steam. It's an electric train.

Franklin lent Darlene as much money as she already had, then she spent $10. The next day, Franklin lent her as much money as she now had and again, she spent $10. On the third day Franklin once again lent her as much money as she now had and she spent $10, leaving her broke. How much money did Darlene start with?

Show the answer » Link$8.75You may have been tempted to guess $30 because $10 is spent three times, but that would mean she would have had $60 ($30 lent plus the $30 she already had), and $50 after spending $10. The rest of the numbers end up at higher than zero, so we know it has to be less than $30. Even starting at $10 leaves Darlene with $10 on the third day. Starting with $8.75 works out as follows.

Day 1: $8.75 (lent) + $8.75 (already had) - $10 (spent) = $7.50 (remaining)Day 2: $7.50 + $7.50 - $10 = $5Day 3: $5 + $5 - $10 = $0

Updated Mar 01, 2013

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