➗ Math

Factorial Calculator

Calculate n! exactly, with every digit, for whole numbers up to 5,000.

Results

n!
2,432,902,008,176,640,000
Number of digits
19

📊 Factorial Calculator chart

log₁₀(n!) — digits grow fast — plotted against n.

What is the Factorial Calculator?

Calculate n! exactly, with every digit, for whole numbers up to 5,000. Factorials grow faster than almost any everyday function, and they are the building blocks of combinations, permutations and probability.

Factorial Calculator – free online math tool illustration
Factorial Calculator — free, exact and private.

How to use the Factorial Calculator

  1. Enter your n.
  2. Results update automatically as you type; you can also press Calculate.
  3. Read the output: n!, number of digits.
  4. Use the 📊 chart to see the result visually, then copy or share it.

Formula and method

n! = n × (n − 1) × … × 2 × 1

Worked example

With n = 20, the Factorial Calculator returns n!: 2,432,902,008,176,640,000; number of digits: 19.

Where the Factorial Calculator helps in real life

You want to know how many different orders 10 books can be arranged on a shelf. 10! gives 3,628,800 arrangements.

A statistics student needs exact factorials for a probability formula. The calculator gives every digit, even for large numbers where ordinary calculators overflow.

Common mistakes to avoid

  • Trying to calculate factorials of negative numbers.
  • Expecting factorials of decimals from this tool.
  • Rounding large factorials and losing precision.
  • Using factorials when a combination formula is needed.

💡 Practical tip: 10! already exceeds 3.6 million, and 20! has 19 digits.

Illustration: a classroom whiteboard with math formulas
Factorial Calculator in everyday work — illustration.

Tips for better results

  • Use combinations when the order of selection does not matter.
  • Remember that 0! equals 1 by definition.
  • Use scientific notation to compare very large factorials.

Frequently asked questions

What does the Factorial Calculator do?

Calculate n! exactly, with every digit, for whole numbers up to 5,000.

How is it calculated?

The Factorial Calculator uses this method: n! = n × (n − 1) × … × 2 × 1.

Can you show an example?

With n = 20, the Factorial Calculator returns n!: 2,432,902,008,176,640,000; number of digits: 19.

Is the Factorial Calculator accurate?

Yes. It uses standard formulas and exact constants, and the results are verified by our automated test suite. Values are displayed to up to 12 significant digits.

Is this tool free and private?

Yes — the Factorial Calculator is completely free with no sign-up, and it runs entirely in your browser, so the values you enter are never uploaded to our servers.

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