Addition and subtraction

problem
Twenty divided into six

Age

7 to 11

Challenge level

Katie had a pack of 20 cards numbered from 1 to 20. She arranged the cards into 6 unequal piles where each pile added to the same total. What was the total and how could this be done?
problem
Rocco's race

Age

7 to 11

Challenge level

Rocco ran in a 200 m race for his class. Use the information to find out how many runners there were in the race and what Rocco's finishing position was.
problem
Throw a 100

Age

7 to 11

Challenge level

Can you score 100 by throwing rings on this board? Is there more than way to do it?
problem
A-magical number maze

Age

7 to 11

Challenge level

This magic square has operations written in it, to make it into a maze. Start wherever you like, go through every cell and go out a total of 15!
problem
One wasn't square

Age

7 to 11

Challenge level

Mrs Morgan, the class's teacher, pinned numbers onto the backs of three children. Use the information to find out what the three numbers were.
problem
Reach 100

Age

7 to 11

Challenge level

Choose four different digits from 1-9 and put one in each box so that the resulting four two-digit numbers add to a total of 100.
problem
Two primes make one square

Age

7 to 11

Challenge level

Can you make square numbers by adding two prime numbers together?
problem
Buckets of thinking

Age

7 to 11

Challenge level

There are three buckets each of which holds a maximum of 5 litres. Use the clues to work out how much liquid there is in each bucket.
problem
The number crunching machine

Age

7 to 11

Challenge level

Put a number at the top of the machine and collect a number at the bottom. What do you get? Which numbers get back to themselves?
problem
Magic triangle

Age

7 to 11

Challenge level

Place the digits 1 to 9 into the circles so that each side of the triangle adds to the same total.