Question

To find 4 times any number, Susan uses the Double-Double strategy (multiply by 2,

then by 2 again). Susan wrote (2 x 9) x 2 to record how she would solve 4 x 9.

Answer 1

Yes that's a valid method

Explanation:

4*9=2*2*9

4*9=36

2*2*9=2*18=36