Grade
5

Which One Doesn’t Belong? Partially Completed Products

Look at this set of four multiplication problems. Decide which one doesn’t belong with the other three. Use math words to describe your thinking. There are many ways to think about each one!

A. An area model for 36 times 46 is missing the partial products for 30 times 6 and 6 times 6. B. In the standard algorithm for 19 times 18, one partial product is blank blank 2. The other is 1 9 blank. The product is 3 blank 2. C. In the standard algorithm for 43 times 38, one partial product is 344. The other is 1290. The product is 1634. D. In the standard algorithm for 51 times 53, one partial product is 1 5 blank. The other is blank blank 5 0. The product is blank 7 0 blank.

Challenge

Find reasons why each of the problems might not belong with the other three.

Share

Explain your thinking to someone else. Do they have different reasons why one doesn't belong?

Printable Version

Google doc for printing and copying

Reference for Educators

Sample problems and solutions