### 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...

### Days and Dates

Investigate how you can work out what day of the week your birthday will be on next year, and the year after...

# Contact Circles

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

The square whose vertices are the centres of the original four circles has side of length 2 units and this distance is equal to the diameter of the circle through $X, Y, Z$ and $T$.

Therefore the radius is 1 unit long.

This problem is taken from the UKMT Mathematical Challenges.