Wander in to the offices of our mathematicians and what do you see? Yes, computers, yes, whiteboards (and the odd blackboard), yes serious concentration on the critical problems in their subject...

But you might also notice something else: toys. Or, to be more specific, mathematical toys.

Are numbers essential for counting? Probably, in a world where we don’t just want to know if something is good, but exactly how good. But it wasn’t always the case.

In this clip from his Vicky Neale Public Lecture, Tim Harford demonstrates that earlier cultures used alternate ways to keep track.