A group of 12 friends meet at a cafe.
Every person in the group buys a small gift for every other person in the group. However, instead of exchanging gifts, they decide to pair up and take one photo of every possible pair of people.
Work out the total number of photos taken.
68 exam-style questions on Edexcel GCSE Maths The Product Rule for Counting. Each one has a worked solution and a mark scheme showing where the marks go.