The 9 times table. Knowing your times tables is really helpful with mental maths and problem solving. You can easily tell whether a number is a multiple of 9 by adding the digits together.

Anyway, I was talking about the nine times table at work the other day - for me, it really is where my maths education pretty much ended, and I'm as ashamed of that as I could be.

Nine-year-olds should recite times tables by heart, says Schools Minister. Nick Gibb says primary schools should adopt Chinese-style teaching methods, with an emphasis on memorising times tables ...