The stand-up comic and celebrity rationalist probably gets as close here as TV can to making maths fun. Fellow egghead Professor Marcus du Sautoy sets O Briain a series of puzzles couched in accessible, practical terms, but which get progressively harder and need real sums to answer. Maths graduate O Briain squeaks out attempted solutions, often rather impressively, on a Waking the Dead-style glass board. Joining him is the obligatory weekly comedian guest – David O’Doherty tonight – cast in the role you’re probably playing at home: shouting answers that might, if you’re lucky, be half-right.