I most certainly didn't know it! But now I do! Thanks Deepti!! Until now, I've always called it the number sign or the slanted tictactoe grid!!

I always called it the number sign or pound key.

they forgot to mention its use as 'sharp' in music

ah, the random things i learn here...had no idea!

ditto, on the random things one learns here. I was wondering why "octo" and there it was: the eight fields surrounding the village (was it?). Wonder why it was adapted (?) as the musical sharp sign?

Ha ha, I've called it a number sign (or sharp) all my life. Never knew that.

Here in Brazil they call it the jogo do velho--their name for Tic-Tac-Toe.

Nope. I remember calling it "Hash"