Addition and subtraction

problem
Crossed ends

Age

11 to 14

Challenge level

Crosses can be drawn on number grids of various sizes. What do you notice when you add opposite ends?
problem
Debasing the coinage

Age

11 to 14

Challenge level

How much lighter will £5 worth of 5p's be with these new lighter coins?
problem
Bus route

Age

11 to 14

Challenge level

How far apart are the first and last bus stops in this bus route?
problem
Mathematical ages

Age

11 to 14

Challenge level

Arrange these three famous mathematicians in order with the shortest-lived first.
problem
Little Goldbach

Age

11 to 14

Challenge level

How many of the numbers 1 to 20 are not the sum of two primes?
problem
Debt recovery

Age

11 to 14

Challenge level

Tony and Tina can't work out which of them owes what to the other. Can you?
problem
Find the difference

Age

5 to 7

Challenge level

Place the numbers 1 to 6 in the circles so that each number is the difference between the two numbers just below it.
problem
Different magic square

Age

11 to 14

Challenge level

Can you solve this magic square?
problem
Shut the box

Age

5 to 7

Challenge level

An old game with lots of arithmetic!
problem
Lengthy journeys

Age

7 to 11

Challenge level

Investigate the different distances of these car journeys and find out how long they take.