### Pebbles

Place four pebbles on the sand in the form of a square. Keep adding as few pebbles as necessary to double the area. How many extra pebbles are added each time?

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!

### GOT IT Now

For this challenge, you'll need to play Got It! Can you explain the strategy for winning this game with any target?

# Weekly Problem 38 - 2010

##### Stage: 3 Short Challenge Level:

Since $100=2\times2\times5\times5$, the only possible product of four different positive integers which equals $100$ is $1\times2\times5\times10$. The sum of these integers is $1+2+5+10 = 18$.

This problem is taken from the UKMT Mathematical Challenges.

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