Significant Figures Calculator
Count & round sig figs.
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Factorial Calculator
Compute n! for any whole number, exact or in scientific notation.
n!
—
Factorial of n.
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How the Factorial Calculator Works
The factorial of a whole number n, written n!, is the product of every whole number from 1 up to n. So 5! = 1×2×3×4×5 = 120. By definition 0! = 1. Factorials grow extremely fast — 10! is already over three million — and they count the number of ways to arrange n distinct items.
This calculator computes exact factorials for reasonable n and switches to scientific notation for very large results, also reporting the number of digits.
n! = 1 × 2 × 3 × … × n
Frequently Asked Questions
What is a factorial?
The product of all whole numbers from 1 to n. 5! = 120. It counts how many ways n distinct things can be arranged.
What is 0 factorial?
0! is defined as 1 — there is exactly one way to arrange nothing.
Why do factorials get so big?
Each step multiplies by a larger number, so they grow faster than any exponential — 20! already exceeds two quintillion.
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