How many of these can you solve?
Each Christmas, the UK intelligence agency GCHQ launches a codebreaking challenge aimed at testing problem solving skills.
This year's puzzle is aimed at children between the age of 11 and 18 and features a variety of brainteasers including codebreaking and maths.
More than 1,000 secondary schools across the UK signed up for the 2023 event, which this year features some of the trickiest puzzles yet.
The aim is to exercise British children's grey matter and to look for new GCHQ recruits.
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