Multiplying And Adding Numbers In The Form: ab + bc
A. From algebra we can factor: ab + bc = b(a + c)
B. Using numbers instead of variables we get the
following:
1. Take out the number that both sides have in common.
2. Add the remaining numbers.
3. Multiply the number in step 1 with the result in step
2 for the answer.
Ex [1] 15 x 12 + 15 x 8 =_________.
a) Rewrite in the form 15 x (12 + 8).
b) 15 x 20 = 300.
c) The answer is 300.
Ex [2] 16 x 16 + 16 x 17 =_________.
a) Rewrite in the form 16 x (16 + 17).
b) 16 x 33 = 48 x 11. See Double and Half.
c) 48 x 11 = 528. See Multiplying by 11.
C. Ex [2] uses a variety of different methods. This is
just how I would do the problem,
but there are many different ways of going about solving
this problem. This is up to
you.