The number nine comes after eight and before ten. When you count nine objects, you have one less than a full group of ten. Nine is written as 9 in numerals or IX in Roman numerals.

Nine shows up in interesting ways throughout life and history. A baseball team fields nine players at a time. In many countries, students attend school for about nine months of the year. The ancient Greeks considered nine a sacred number because it's three times three, and three was special to them. When someone says they're “dressed to the nines,” they mean they look especially sharp and well-dressed.

In multiplication, nine has a neat trick: the digits in its multiples up to 9 × 10 add up to nine. Try it: 9 × 2 = 18 (1 + 8 = 9), 9 × 3 = 27 (2 + 7 = 9), 9 × 4 = 36 (3 + 6 = 9). This pattern works through 9 × 10 = 90.

You might also hear someone say they have “nine lives” like a cat, meaning they've survived dangerous situations that might have finished someone else. When something is saved “in the nick of time,” people sometimes call it a ninth-inning save, referring to baseball's final inning when everything is on the line.