Practicing Multiplication

In Math, we are using flashcards to review multiplication combinations we know and to identify the ones we need to work on. We are developing strategies for solving unknown multiplication combinations, like using a “starting with” combination. For example, many of us agreed that 9 x 12 is tricky. Imagine 9 x 12 as an array. There are many different ways to cut up the array to make this an easier problem.

Some of us chose to start with 9 x 10 = 90. Then we add 9 x 2 to find the answer.
90 + 18 =108. Note how this looks on an array.

There are other ways to start this problem. Some of us split the 12 up into a 6 and a 6, and solve the problem by figuring out (9 x 6) + (9 x 6). 54 + 54 = 108.

For these first examples, we kept the 9 and split up the 12.   Some of us saw this problem differently, and kept the 12 and split up the 9. Here is an example of (3 x 12) + (3 x 12) + (3 x 12).

Those of us who already automatically know all of our multiplication to 12 x 12 are applying this strategy to mentally solve double digit times single digit multiplication problems. For example, to solve 19 x 6, I can break up the 19 into 10 and 9:

10 x 6 = 60
9 x 6 = 54
60 + 50 + 4 = 114

Home/School Connection:  Which multiplication problems are a little tricky for you?  How do you solve them mentally?  Tell us about it on the blog!  If you are stuck, use grid paper to draw the array and actually cut it into parts.  When you have an array, you can always use a strategy to find a product!