Calculator
What the Factorial Calculator does
Factorial Calculator: calculates n! from n (0 to 170). Example: n (0 to 170) 10 gives n! 36,28,800.
n!, derived from n (0 to 170). Results refresh instantly, so trying variations costs nothing but a moment.
A second opinion on a calculation takes seconds and prevents errors compounding. That is usually what brings students checking homework here.
This runs client-side, which means we never receive what you enter and could not retrieve it if asked.
If you want to check the arithmetic, the field table, the method and a worked example are further down.
What do the Factorial Calculator fields mean?
The Factorial Calculator uses 1 input. A complete set of starting values is loaded for you, so nothing is required before the first result appears.
| Field | What to enter | Default |
|---|---|---|
| n (0 to 170) | accepts 0 to 170 | 10 |
How does the Factorial Calculator work?
Each output is derived from the inputs above in a single pass; there is no hidden state carried between runs, so the same inputs always give the same calculation.
The guard clauses run before the formula does, which is why mistakes surface next to the field.
Worked example
These are the values the Factorial Calculator loads by default, and the result it produces from them. This walkthrough uses the starting values, which means you can follow along without typing anything.
| n (0 to 170) | 10 |
|---|
| n! | 36,28,800 |
|---|---|
| What this means | 10! = 3628800 |
Beyond the formula: factorials
Factorials grow explosively fast, 10! is about 3.6 million, but 20! already exceeds a quintillion, which is why this calculator caps input at 170, beyond which the result exceeds what a standard number can represent precisely in JavaScript.
Common mistakes and sanity checks
- By definition, 0! = 1, not 0: a common point of confusion, but mathematically necessary for formulas like permutations and combinations to behave correctly at the boundary case of choosing nothing.
- Factorials are the basis of permutations (arranging items in order) and combinations (choosing items without regard to order). If you’re really trying to count arrangements or selections rather than compute a raw factorial, the dedicated permutation or combination calculator is the more direct tool.
- Beyond n=170, factorials exceed the largest number JavaScript can represent and become "Infinity": genuinely large factorials in mathematics or cryptography need arbitrary-precision arithmetic libraries rather than a standard calculator.
How to use it
- Fill in n (0 to 170) (0 to 170).
- Watch the results panel as you type: it recalculates on every keystroke.
- The panel reports n! and What this means.
- Share the link rather than a screenshot. It carries the values with it.
What this tool does not do
- Displayed values are rounded; the underlying calculation keeps full precision.
- Very large or very small values reach the limits of floating-point precision, about 15 significant digits.
- Assumptions built into the method are stated above, but they are still assumptions.
Frequently asked questions
n (0 to 170). That is the whole form. Each field is pre-filled with a sensible default, letting you treat it as a what-if tool rather than a data-entry form.
n (0 to 170) accepts 0 to 170. If a value falls outside, the tool says which field is at fault instead of guessing.
With the values loaded when the page opens, n! comes out as 36,28,800. Change a value and the number is recomputed on the spot.
No record is kept. We never receive what you type, so there is nothing on our side to retain.
It is free to use, with no premium tier holding back the useful parts.
Reliable for the case described. Where more than one convention exists, the method section says which one is used.