Addition and subtraction

problem
Highest and lowest

Age

7 to 11

Challenge level

Put operations signs between the numbers 3 4 5 6 to make the highest possible number and lowest possible number.
problem
Clever keys

Age

7 to 11

Challenge level

On a calculator, make 15 by using only the 2 key and any of the four operations keys. How many ways can you find to do it?
problem
Zios and Zepts

Age

7 to 11

Challenge level

On the planet Vuv there are two sorts of creatures. The Zios have 3 legs and the Zepts have 7 legs. The great planetary explorer Nico counted 52 legs. How many Zios and how many Zepts were there?
problem
Abundant numbers

Age

7 to 11

Challenge level

48 is called an abundant number because it is less than the sum of its factors (without itself). Can you find some more abundant numbers?
problem
Super shapes

Age

7 to 11

Challenge level

The value of the circle changes in each of the following problems. Can you discover its value in each problem?
problem
Oranges and lemons

Age

7 to 11

Challenge level

On the table there is a pile of oranges and lemons that weighs exactly one kilogram. Using the information, can you work out how many lemons there are?
problem
Back to school

Age

7 to 11

Challenge level

Mr. Sunshine tells the children they will have 2 hours of homework. After several calculations, Harry says he hasn't got time to do this homework. Can you see where his reasoning is wrong?
problem
Dividing a cake

Age

7 to 11

Challenge level

Annie cut this numbered cake into 3 pieces with 3 cuts so that the numbers on each piece added to the same total. Where were the cuts and what fraction of the whole cake was each piece?
problem
Penta post

Age

7 to 11

Challenge level

Here are the prices for 1st and 2nd class mail within the UK. You have an unlimited number of each of these stamps. Which stamps would you need to post a parcel weighing 825g?
problem
The clockmaker's birthday cake

Age

7 to 11

Challenge level

The clockmaker's wife cut up his birthday cake to look like a clock face. Can you work out who received each piece?