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A Dotty Problem

Age 7 to 11 Challenge Level:

A Dotty Problem

Starting with the number $180$, take away $9$ again and again, joining up the dots as you go.

Watch out - don't join all the dots!

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Why do this problem?

This problem is a different way of practising the nine times table. It also provides a context in which you can discuss mental strategies for taking away nine.

Key questions

What do you get if you take away nine from that number?
How could you work it out?
Can you think of another way to do it?

Possible extension

Children could make their own version for counting backwards in twelves.