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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?

# The Queen of Hearts

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

The Queen of Hearts has lost her tarts! She is sure that those knaves who have not eaten the tarts will tell her the truth and the guilty knave will tell lies. When questioned the five knaves declare:

Knave 1
One of us ate them

Knave 2
Two of us ate them

Knave 3
Three of us ate them

Knave 4
Four of us ate them

Knave 5
Five of us ate them

How many of the knaves were honest?

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

This problem is taken from the UKMT Mathematical Challenges.