What is the largest number this calculator can handle?

You can enter values up to 1,000,000. Exact values are shown for n up to 1,000; beyond that, the result is far too large to display in full, so you get the digit count and scientific notation instead.

Why can't I enter a negative number or a decimal?

Factorials are only defined for non-negative integers in elementary arithmetic. The Gamma function extends the concept to non-integers, but that's a separate calculation this tool doesn't perform.

How many digits does 100! have?

100! has 158 digits. You can verify this — and see the digit count for any input — instantly using this calculator.

What does 'scientific notation' mean for a factorial result?

For very large factorials, the exact digit sequence isn't practical to display, so the result is shown as a mantissa times a power of 10 (e.g., 9.3326e+157 for 100!), which conveys the magnitude precisely.

Is 0! really equal to 1?

Yes. By mathematical convention, the factorial of 0 is defined as 1 — it represents the number of ways to arrange zero items, which is exactly one way (doing nothing).

Where are factorials used in real life?

Factorials appear constantly in combinatorics (permutations and combinations), probability theory, series expansions in calculus, and computer science algorithms that involve arranging or ordering items.

Does this calculator show the multiplication steps?

Yes, for smaller inputs you'll see the full expansion (e.g., 5! = 5 × 4 × 3 × 2 × 1). For larger inputs, the step panel explains how the result was computed instead of listing every multiplication.

Factorial Calculator — Instant n! With Step-by-Step Expansion

Our Factorial Calculator computes n! for any non-negative integer, from small values like 5! = 120 up to enormous numbers like 1,000,000!. For smaller inputs you get the exact value with a step-by-step multiplication breakdown; for very large inputs — where the exact number would have millions of digits — you get the precise digit count and scientific notation instead, so you always know the scale of the result.

Quick Answer

The factorial of a non-negative integer n, written n!, is the product of all positive integers from 1 to n (e.g., 5! = 120). This calculator computes exact values for smaller inputs and switches to scientific notation with a precise digit count for inputs too large to display in full, up to n = 1,000,000.

Enter a non-negative integer (n)

Enter a number and click Calculate.

Quick Reference

120

720

5,040

40,320

362,880

10!

3,628,800

How to Use the Factorial Calculator — Calculate n! Online

1
Enter a non-negative whole number (0 to 1,000,000) into the input field.
2
Click 'Calculate' to compute the factorial.
3
View the exact value for smaller numbers, or the scientific notation and digit count for very large ones.
4
Check the step-by-step expansion to see exactly how the result was built.
5
Click 'Copy' to copy the exact value or scientific notation to your clipboard.

Why Use Factorial Calculator — Calculate n! Online?

Factorials grow faster than almost any other common function — 20! already exceeds a quintillion, and 170! is the largest factorial a standard 64-bit float can represent exactly. Manually multiplying a growing chain of numbers is slow and error-prone, and most basic calculators overflow well before you reach genuinely large inputs. Our calculator uses exact big-integer arithmetic for moderate values and precise logarithmic estimation for huge ones, so you get a correct answer — or an accurate digit count and scientific notation — no matter how large n gets.

Frequently Asked Questions

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