#### You may also like

List any 3 numbers. It is always possible to find a subset of adjacent numbers that add up to a multiple of 3. Can you explain why and prove it?

### Magic Sums and Products

How to build your own magic squares.

### Weekly Problem 3 - 2013

Weekly Problem 3-2013

# Weekly Problem 2 - 2013

##### Stage: 3 Challenge Level:
Your answer will be a multiple of $7$.

Let the number thought of be $x$. Then the final number is $$4(2x + 3) - 5- x = 7x + 7 = 7(x+ 1)$$

This problem is taken from the UKMT Mathematical Challenges.

View the previous week's solution
View the current weekly problem