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Adding All Nine

Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some other possibilities for yourself!

Have You Got It?

Can you explain the strategy for winning this game with any target?

Counting Factors

Is there an efficient way to work out how many factors a large number has?

Gabriel's Problem

Age 11 to 14
Challenge Level

The puzzles are available for classroom display as slides, in PowerPoint or PDF format.

This printable worksheet may be useful: Gabriel's Problem.

This spreadsheet may also be useful.

A poster of this problem is available here.