Odd and even numbers

I added together some of my neighbours' house numbers. Can you explain the patterns I noticed?

Can you find examples of magic crosses? Can you find all the possibilities?

In this calculation, the box represents a missing digit. What could the digit be? What would the solution be in each case?

In this game for two players, the idea is to take it in turns to choose 1, 3, 5 or 7. The winner is the first to make the total 37.

Can you put the numbers in the correct place in this Carroll diagram?

Look at what happens when you take a number, square it and subtract your answer. What kind of number do you get? Can you prove it?

What happens when you add three numbers together? Will your answer be odd or even? How do you know?

This problem looks at how one example of your choice can show something about the general structure of multiplication.

This investigates one particular property of number by looking closely at an example of adding two odd numbers together.

Charlie has made a Magic V. Can you use his example to make some more? And how about Magic Ls, Ns and Ws?