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?

Number Differences

Stage: 2 Challenge Level: Challenge Level:1

You might like to try A Ring of Numbers and More Rings of Numbers before this problem.

Place the numbers from 1 to 9 in the squares below so that the difference between joined squares is odd. (You must use each of the numbers once.)
Can you find some other ways to do this? Explain how you do this.

Can you put the numbers in the squares so that the difference between joined squares is even?
Explain your answer.

What general statements can you make about odd and even numbers?

Full size version
This text is usually replaced by the Flash movie.

This problem is based on an idea taken from "Apex Maths Pupils' Book 2" by Ann Montague-Smith and Paul Harrison, published in 2003 by Cambridge University Press. To order a copy of this book,  see their online catalogue.