### 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?

# Gridlines

##### Stage: 3 and 4 Short Challenge Level:
See all short problems arranged by curriculum topic in the short problems collection

There are lots of ways of choosing three dots from this $4$ by $4$ array.

How many triples of points are there where all three lie on a straight line (not necessarily equally spaced)?

If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.

This problem is taken from the UKMT Mathematical Challenges.