Addition and subtraction

problem

Calendar Calculations

Age

7 to 11

Challenge level

2 out of 3

Try adding together the dates of all the days in one week. Now multiply the first date by 7 and add 21. Can you explain what happens?
problem

Spell by Numbers

Age

7 to 11

Challenge level

2 out of 3

Can you substitute numbers for the letters in these sums?
problem

Code Breaker

Age

7 to 11

Challenge level

2 out of 3

This problem is based on a code using two different prime numbers less than 10. You'll need to multiply them together and shift the alphabet forwards by the result. Can you decipher the code?
problem

Arrange the Digits

Age

11 to 14

Challenge level

2 out of 3

Can you arrange the digits 1,2,3,4,5,6,7,8,9 into three 3-digit numbers such that their total is close to 1500?
problem

Jugs of Wine

Age

11 to 14

Challenge level

2 out of 3

You have four jugs of 9, 7, 4 and 2 litres capacity. The 9 litre jug is full of wine, the others are empty. Can you divide the wine into three equal quantities?
problem

Homes

Age

5 to 7

Challenge level

1 out of 3

Six new homes are being built! They can be detached, semi-detached or terraced houses. How many different combinations of these can you find?
problem

Fair Exchange

Age

5 to 7

Challenge level

1 out of 3

In your bank, you have three types of coins. The number of spots shows how much they are worth. Can you choose coins to exchange with the groups given to make the same total?
problem

Planet Plex Time

Age

5 to 7

Challenge level

1 out of 3

On Planet Plex, there are only 6 hours in the day. Can you answer these questions about how Arog the Alien spends his day?
problem

Money Line-Up

Age

5 to 7

Challenge level

1 out of 3

In this game for two players, the aim is to make a row of four coins which total one dollar.
problem

Unit Differences

Age

5 to 7

Challenge level

1 out of 3

This challenge is about finding the difference between numbers which have the same tens digit.