A group of 18 friends meet at a party.
Each friend gives every other friend exactly one high-five.
Work out the total number of high-fives that occur.
Practise Edexcel GCSE Maths The Product Rule for Counting with exam-style questions for Foundation and Higher tier. 68 questions, matched to the Edexcel GCSE Maths (1MA1) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.