### Consecutive Numbers

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

### Calendar Capers

Choose any three by three square of dates on a calendar page...

### Building Tetrahedra

Can you make a tetrahedron whose faces all have the same perimeter?

# 11x11 Square

##### Age 11 to 16Challenge Level

There's an interesting trick you can do with an $11 \times 11$ square...

It's possible to make five rectangles, each with different widths and lengths, using each of the following dimensions once only: $1, 2, 3, 4, 5, 6, 7, 8, 9, 10$, that can be used to tile the $11 \times 11$ square!

Convince yourself that only one of the arrangements below could satisfy these conditions.

Can you find the dimensions of the five rectangles which can tile the $11 \times 11$ square?

Can you find all the possible different solutions?
Here different means not a reflection or rotation of another solution.

With thanks to Don Steward, whose ideas formed the basis of this problem.