Grade
5

Which One Doesn't Belong? Expanding Twos

Look at this set of four numbers. 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. shows the number 2.222. B. shows the expression (2 times 1) + (2 times 0.1) + (2 times 0.01). C. shows the expression (2 times 1) + (2 times 0.1) + (2 times 0.001). D. shows the expression (2 times 10) + (2 times 1) + (2 times 0.1) + (2 times 0.01).

Challenge

Find reasons why each of the numbers or expressions 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

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Reference for Educators

Sample problems and solutions