You may also like

Card Trick 2

Can you explain how this card trick works?

The Patent Solution

A combination mechanism for a safe comprises thirty-two tumblers numbered from one to thirty-two in such a way that the numbers in each wheel total 132... Could you open the safe?


A bag contains 12 marbles. There are more red than green but green and blue together exceed the reds. The total of yellow and green marbles is more than the total of red and blue. How many of each colour there are in the bag?

Calendar Capers

Age 11 to 14 Challenge Level:

Is there a quick way to work out the totals without having to add everything up?

If you know just one date in your three by three square, how can you work out the other eight dates?

Algebra might be helpful...