When I was a kid we used to phone people whose phone numbers were mathematically interesting. This was in the North-East of England (Sunderland), and we were often amazed at the responses. You'd ring some lady out of the blue and tell her that her phone number was a power of three, or something, and she'd say, "well is that right! I never knew. How interesting."

We always thought we'd just get told to bugger off. Rarely was that the case.

By some odd coincidence, I've since moved to the other side of the world but I sit and type this message in the old living room in Sunderland where many of those calls were made.