Yes, the numbers game. My ID card was EKBB1384, ATC number 304xxxx, RAF 350xxxx, Op number at a RAF Y station 661, I have both a 10-digit NHS number and a Hospital Patient number Fxxxxx. I can quote each correctly at the drop of a hat except the NHS one. Oh, I forgot, there's yet another one, ZL xx xx xx C, which the tax man knows. I probably also have one squirreled away in some office in Brussels, until UKIP take over.