Addition and subtraction

Investigate what happens when you add house numbers along a street in different ways.

Find out why these matrices are magic. Can you work out how they were made? Can you make your own Magic Matrix?

Delight your friends with this cunning trick! Can you explain how it works?

What is the value of c in this subtraction?

Try grouping the dominoes in the ways described. Are there any left over each time? Can you explain why?

Can you hang weights in the right place to make the the number balance balanced?

Are these domino games fair? Can you explain why or why not?

Weekly Problem 49 - 2013
What is the value of 2000 + 1999 × 2000?

If you take a three by three square on a 1-10 addition square and multiply the diagonally opposite numbers together, what is the difference between these products. Why?

Have a go at this game which involves throwing two dice and adding their totals. Where should you place your counters to be more likely to win?