What Does an Exclamation Mark Mean in Math?

An exclamation mark after a number in mathematics denotes a factorial expression. This means that the number must be multiplied by all its lesser integers. Here is an example of how to work through a factorial.

Step One

Let's take the number 4 for an example.

If you see 4!, first translate it into 4 x 3 x 2 x 1.

Step Two

For the second step, multiply the numbers all together.

4 x 3 x 2 x 1 = 24.

So 4! = 24.

Considerations

Factorials operate on the same process no matter how big the number. Bigger numbers are most easily done with a calculator to avoid making mistakes.

Also, it's important to remember that 0! is actually 1. The explanation for this is that there are no integers less than 0, so you just end up with the multiplicative identity of 1, according to the Math Less Traveled website.

References

• Math Less Traveled: Factorial!