Addition and subtraction

problem

Special 24

Age

7 to 11

Challenge level

Find another number that is one short of a square number and when you double it and add 1, the result is also a square number.
problem

Zargon Glasses

Age

7 to 11

Challenge level

Zumf makes spectacles for the residents of the planet Zargon, who have either 3 eyes or 4 eyes. How many lenses will Zumf need to make all the different orders for 9 families?
problem

Magic Circles

Age

7 to 11

Challenge level

Put the numbers 1, 2, 3, 4, 5, 6 into the squares so that the numbers on each circle add up to the same amount. Can you find the rule for giving another set of six numbers?
problem

Arranging the Tables

Age

7 to 11

Challenge level

There are 44 people coming to a dinner party. There are 15 square tables that seat 4 people. Find a way to seat the 44 people using all 15 tables, with no empty places.
problem

Number Juggle

Age

7 to 11

Challenge level

Fill in the missing numbers so that adding each pair of corner numbers gives you the number between them (in the box).
problem

A Rod and a Pole

Age

7 to 11

Challenge level

A lady has a steel rod and a wooden pole and she knows the length of each. How can she measure out an 8 unit piece of pole?
problem

Add 3 Dice

Age

7 to 11

Challenge level

Three dice are placed in a row. Find a way to turn each one so that the three numbers on top of the dice total the same as the three numbers on the front of the dice. Can you find all the ways to do this?
problem

Next Number

Age

7 to 11

Challenge level

Find the next number in this pattern: 3, 7, 19, 55 ...
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?