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Noah saw 12 legs walk by into the Ark. How many creatures did he see?

Unit Differences

Age 5 to 7
Challenge Level

This challenge is about finding the difference between numbers which have the same tens digit.

Here are two examples where I’ve decided to use numbers which have two tens:



The number above is always the difference between the two beneath it.

Can you find different pairs of numbers with a difference of 1 or 2 or 3 or 4 ... and so on?

Can you find more than one way of doing it?
The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.
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