before learning how to do double digit multiplication, let’s review what multiplication is
TRANSCRIPT
Before learning how to do double digit
multiplication, let’s review what
multiplication is...
Let’s choose a problem:Let’s choose a problem:
15*17 means:
15 groups of 17
oror17+17+ 17+ 17+ 17+17+17+ 17+ 17+ 17+
17+ 17+ 17+ 17+ 17+17+ 17+ 17+ 17+ 17+
17+ 17+ 17+ 17+ 1717+ 17+ 17+ 17+ 17
To solve 15*17, we can use base ten base ten blocksblocks to find the
answer...
Devin and Peter are building 15 groups or rows of 17.
Emily and Travis use a corner piece to Emily and Travis use a corner piece to line up their problem in neat rows and line up their problem in neat rows and columns.columns.
Kevin and Patrick decide to use rods to show “tens” and unit cubes to show “ones.”
Alyssa
Erin
JordanMichael
15 groups or rows
17 in each group
15
17
Now that you have built 15 * 17, you
can see the4 different products4 different products
that are created:
10 + 7
10 + 5
10 * 10 = 10 * 7 =
5 * 10 = 5 * 7 =
100
70
50
+ 35
255
If we add up all of the products, we get:
By buildingbuilding the multiplication problem, we can see the answer beautifully, but it does take a lot of time and materials to do so. A
shorter method is to drawdraw the multiplication problem using
graph paper...
Erin lines up 15 rows and 17 columns on graph paper.
Devin extends the lines and colors each of the four sections in a different color.
Kevin shows what 15 * 17 looks like as a picture. Did he get the same answer?
Here is the picture for 15 * 17. Notice that there are 15 rows of 17 & that 4 sections are created by this problem:
Do we get the same answer?
100
7050
+ 35
255
Drawing a picture of a multiplication problem works, too, but it does take time to draw and
color the picture. Is there a shorter way?
15 * 17 should remind you of
MULTIPLICATION MULTIPLICATION WRESTLING!WRESTLING!
Do these numbers look familiar?
So you can solve double digit multiplication
problems using Multiplication WrestlingMultiplication Wrestling, but there are otherother ways,
too...
One shortcut methodis called
PARTIAL PARTIAL PRODUCTS:PRODUCTS:
These numbers should look familiar!
Another method is called the
SHORTCUT SHORTCUT METHOD...METHOD...
35 + 5070 + 100
These numbers should look familiar!
There are many ways to solve Double Digit
Multiplication problems. Choose the method that
works for you. “There’s more than one “There’s more than one
way to skin a cat!”way to skin a cat!”