Follow the clues to find the mystery number.
You have 4 red and 5 blue counters. How many ways can they be
placed on a 3 by 3 grid so that all the rows columns and diagonals
have an even number of red counters?
You can trace over all of the diagonals of a pentagon without
lifting your pencil and without going over any more than once. Can
the same thing be done with a hexagon or with a heptagon?
Well done - you're spot on and in fact that means there are many solutions - thousands! Taranjot and Amrita at Alexandra Junior School point out that:
Harmohan, Akash and Ayman also from Alexandra School came up with some general rules about odd and even numbers:
Thank you to all those of you who sent in solutions.