Making 11p
How many ways are there to make 11p using 1p, 2p and 5p coins?
Age
11 to 14
Challenge level
Problem
5p, 2p and 1p coins (or a mixture of any or all of these) are used to make a total of 11p. In how many different ways can this be done?
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
Student Solutions
11
With no 5p coins, there could be 0, 1, 2, 3, 4 or 5 2p coins,
i.e. 6 possible ways.
With one 5p coin, there could be 0, 1, 2 or 3 2p coins, i.e. 4
possible ways.
With two 5p coins, there can be no 2p coins, i.e. 1 possible
way.