Test your code-cracking skills against these science-themed puzzles from Brian Clegg's new book, Conundrum.
Are you a master at cracking codes? Prove your ability with this hand-picked selection of science-themed puzzles from Conundrum by Brian Clegg (£8.99, Icon Books).
So, grab a pen and paper and give your brain a workout. Challenge your friends and remember to let us know how you did on Twitter at @sciencefocus.
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