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## 'Pairs of Numbers' printed from http://nrich.maths.org/

If you have ten counters numbered $1$ to $10$, how many can you put into pairs that add to $10$?

Can you use them all?

Say how you got your answer.

Now put the counters into pairs to make $12$.

- Can you use them all?
- Say how you got your answer.

Now put the counters into pairs to make $13$.

- Can you use them all?
- Say how you got your answer.

Now put the counters into pairs to make $11$.

- Can you use them all?
- Say how you got your answer.