I’ve been out of school for decades, and I don’t spend my days solving equations (I’m more of a word person). Still, I like to think I have a solid grip on basic math: I can usually gauge whether a ...

If you fancy yourself as a budding spy, GCHQ’s Christmas challenge will put your analytical skills to the test. The UK spy agency, which sets an annual quiz aimed at children aged between 11 and 18, ...