Festive maths puzzles – answers and explanations

Here are the answers to the festive maths quiz I set on December 23. I hope you enjoyed it.

Read more: The magic of maths: festive puzzles to give your brain and imagination a workout

nestdesigns/Shutterstock

Puzzle 1: You are given nine gold coins that look identical. You are told that one of them is fake, and that this coin weighs less than the real ones. Using a set of old-fashioned balance scales...