Squaring Numbers Ending in 5Presented by Grey Matters Mental Gym

http://members.cox.net/beagenius/

Squaring Numbers Ending in 5

• Squaring a number is simply multiplying it by itself. For example, 8 squared (82) is simply 8 * 8, or 64. Conversely, the square root of 64 would be 8.

Squaring numbers ending in 5 are particularly easy. It’s also useful in extracting the square root of any number.

Squaring Numbers Ending in 5

• Have a spectator give you any number from 1 to 100 that ends in 5.

Imagine being able to figure the square of that number in your head!

Squaring Numbers Ending in 5 Requirements

• Calculator

Spectator

Squaring Numbers Ending in 5

To be able to square numbers ending in 5 mentally, you must know your times tables up to 10 times 10.

Squaring Numbers Ending in 5

• When you’re given a two-digit number ending in 5, focus on the digit in the tens place.

For example, let’s say you’re given the number 35. In this case, you would focus on the 3.

Squaring Numbers Ending in 5

• Simply multiply the tens digit by a number 1 higher than itself.

Since we’re focusing on the “3” in 35, we would multiply 3 time 4 (1 higher than 3) to get 12.

Squaring Numbers Ending in 5

• To finish, simply add “25” to the end of the number you just calculated. That’s the answer!

• Taking 35, we focused on the “3”, multiplying 3 times 4 to get 12. Adding “25” to the end gives 1,225, which is the answer to 35 squared (352).

Squaring Numbers Ending in 5

• Other examples:• What is 752? 7 times 8 is 56, so the

answer is 5,625.

Squaring Numbers Ending in 5

• Other examples:• What is 852? 8 times 9 is 72, so the

answer is 7,225.

Squaring Numbers Ending in 5

• Other examples:• What is 952? 9 times 10 is 90, so the

answer is 9,025.