You may also like

problem icon

Number Detective

Follow the clues to find the mystery number.

problem icon

Red Even

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?

problem icon

Prime Magic

Place the numbers 1, 2, 3,..., 9 one on each square of a 3 by 3 grid so that all the rows and columns add up to a prime number. How many different solutions can you find?

Becky's Number Plumber

Age 7 to 11 Challenge Level:
What have you noticed about the answers each time?
What do they have in common?
What do you know about multiplying by $5$?
Can you explain why these patterns occur?