Only a math nerd will understand

Why all the down votes when you're right?

A number with a ! (factorial) after it means that you multiply it by all of the numbers less than it, disregarding 0 or negative numbers. For example 6!=6x5x4x3x2x1=720. Does this help?

yeah, i knew the ! meant it was gonna be higher

Does anyone know why factorials are used/useful? We've just started them at school, and I don't really see the point.

@juliaaaa factorials are used to find combinations of things. As an example, say you wanted to find out how many different ways you could arrange the numbers 1 2 and 3. There are 3 different numbers, so you could just do 3! (3 * 2 * 1) and find out its 6. Or you could do it the long way and write them all out, 123, 132, 213, 231, 312, 321. If you add one more number onto it (1234) it increases the number of combinations to 24 different ones, 5 numbers makes it 120 combinations, and so on. Its also used some in more advanced mathematics too, but thats the most common one, especially when learning it in school.

Im 32 years old and have 3 graduate degrees and I've never once heard an "!" After a number means you multiply it by everything below it... Also for a grammar nazi you should know how to use a question mark properly.

I'm in tenth grade and we haven't learned this yet. In fifth grade we were learning how to divide, idk maybe that's just my school.