You may also like

Prompt Cards

These two group activities use mathematical reasoning - one is numerical, one geometric.

Consecutive Numbers

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

Exploring Wild & Wonderful Number Patterns

EWWNP means Exploring Wild and Wonderful Number Patterns Created by Yourself! Investigate what happens if we create number patterns using some simple rules.

Zargon Glasses

Age 7 to 11
Challenge Level

Here's a solution from Matthew (Nimbin Central School, Australia). He found that 252 lenses would be needed to make all the glasses. He explained how he did it by first working out all the combinations of glasses that made up the 9 orders:

"I wrote down in a grid that was eight wide and nine down, 3 or 4 and we had to be careful not to get the same number of threes or fours as another group of eight. And at the end we found out that there were 36 fours and 36 threes, and when we added all of the numbers together it equalled 252".

Is there another way to do the maths in this problem?