Addition and Subtraction: Age 7-11

This is part of our collection of favourite rich tasks arranged by topic.

If you are a teacher, you can find the whole collection on our Primary Curriculum teacher page.
Alternatively, if you are a student, you'll find the same problems on our Primary Curriculum student page.

problem
Favourite

Diagonal Sums

Age

7 to 14

Challenge level

In this 100 square, look at the green square which contains the numbers 2, 3, 12 and 13. What is the sum of the numbers that are diagonally opposite each other? What do you notice?
problem
Favourite

Three Neighbours

Age

7 to 14

Challenge level

Take three consecutive numbers and add them together. What do you notice?
problem
Favourite

Cubes Within Cubes

Age

7 to 14

Challenge level

We start with one yellow cube and build around it to make a 3×3×3 cube with red cubes. Then we build around that red cube with blue cubes and so on. How many cubes of each colour have we used?
problem
Favourite

Two and Two

Age

7 to 16

Challenge level

How many solutions can you find to this sum? Each of the different letters stands for a different number.