CalcArcade.

Factorial Calculator

Enter a whole number from 0 to 170. You get its factorial, how many digits it has, how many zeros it ends with and its value in scientific notation.

Your numbers

Result

How we calculate it

The factorial of n, written n!, is the product of every whole number from 1 to n: n! = 1 × 2 × 3 × … × n. By definition, 0! = 1.

The calculator multiplies the numbers out exactly, then counts the digits and the zeros at the end. Up to 20! the exact value is shown, and above that the value is shown in scientific notation. For example 10! = 3,628,800, which has 7 digits and 2 trailing zeros.

Assumptions and limits

  • Factorials grow very quickly. 170! is about 7.2574 × 10^306, the largest factorial that fits in a standard number, so 170 is the limit.
  • Only whole numbers of 0 or more have a factorial in this calculator.
  • The count of trailing zeros equals the number of times 5 divides into the factors, which is why it grows slowly.

Frequently asked questions

Why is 0 factorial equal to 1?

It is a definition that keeps the formulas for arrangements and combinations working. There is exactly one way to arrange zero things, so 0! is 1.

What are factorials used for?

They count the ways to arrange things. Five different books can be put in order in 5! = 120 ways. They also appear in probability, combinations and series.

Why does the calculator stop at 170?

The value of 171! is larger than the biggest number a standard calculation can hold, which is about 1.8 × 10^308. Up to 170 the result is still accurate in scientific form.

Related calculators

Worked example (a fixed example using the starting numbers, it does not change as you type)

Inputs: Whole number (0 to 170) = 10.

  • Factorial 3,628,800
  • Number of digits 7
  • Trailing zeros 2
  • Scientific notation 3.6288 × 10^6

Embed this calculator

Add this calculator to your own page. Paste the code where you want it. The small link keeps credit to the source.

More math calculators

Last reviewed: . Formulas and assumptions are described on our methodology page. For information only; not professional advice.