MasterTool

Factorial Calculator

Calculate factorial instantly in your browser.

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What this tool does

Calculate factorial instantly in your browser. Exact BigInt arithmetic — 20! = 2,432,902,008,176,640,000 with no rounding, and values up to 5000! are supported.

How to use the Factorial Calculator

  1. Enter or select whole number n.
  2. Read the calculated result; change any measurement to compare alternatives.

Formula

n! = n × (n−1) × … × 2 × 1, with 0! = 1 by definition; computed with arbitrary-precision BigInt so large factorials are exact, digit for digit.
x
Whole number n

Exact BigInt arithmetic — 20! = 2,432,902,008,176,640,000 with no rounding, and values up to 5000! are supported.

Worked example

For factorial calculator, the following measurements illustrate the exact method: Whole number n: 20.

Inputs

  • Whole number n20

Result

  • 20!2432902008176640000
  • Number of digits19
  • Number of trailing zeros4

Results explained

20!
20! from the formula above. Exact BigInt arithmetic — 20! = 2,432,902,008,176,640,000 with no rounding, and values up to 5000! are supported.
Number of digits
Number of digits from the formula above. Exact BigInt arithmetic — 20! = 2,432,902,008,176,640,000 with no rounding, and values up to 5000! are supported.
Number of trailing zeros
Number of trailing zeros from the formula above. Exact BigInt arithmetic — 20! = 2,432,902,008,176,640,000 with no rounding, and values up to 5000! are supported.

Frequently asked questions

n! = n × (n−1) × … × 2 × 1, with 0! = 1 by definition; computed with arbitrary-precision BigInt so large factorials are exact, digit for digit.

Exact BigInt arithmetic — 20! = 2,432,902,008,176,640,000 with no rounding, and values up to 5000! are supported.

Where mathematically meaningful, yes. Fields specify permitted ranges and undefined operations display an error.

Exact integer calculations use safe integers; decimal calculations use browser floating point, so small rounding differences can occur.

All values remain in your browser and are never uploaded.