Factorial Calculator
Use our factorial calculator to compute n! instantly, even for large values. Includes what factorial means, how factorial works, how to calculate factorial on a calculator (including TI-30X, TI-83, and TI-84), where the factorial button is, and what 1000 factorial looks like in scientific notation.
What is a Factorial?
A factorial (written as n!) is the product of all positive integers from 1 up to n. It grows extremely fast, which is why large factorials are often displayed in scientific notation.
If you’re wondering what factorial means or how factorial works, think of it as repeated multiplication: 5! = 5×4×3×2×1.
Factorials are used in counting, permutations, combinations, probability, and many areas of algebra and calculus.
Factorial Formula
The factorial of a non-negative integer n is defined as a product. A special case is 0! which equals 1.
Defined for non-negative integers n.
By definition, 0 factorial equals 1.
Multiply all integers from 1 to 6.
Even 20 factorial is already far larger than most everyday numbers.
How to Use the Factorial Calculator
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Enter a non-negative integer n.
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The calculator computes n! (factorial).
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For very large results, the calculator may show scientific notation (for example, 3.2e+10).
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Use the result for permutations, combinations, probability, or any factorial-based formula.
Frequently Asked Questions
Factorial (n!) means multiply all positive integers from 1 up to n. Example: 5! = 5×4×3×2×1.
It’s repeated multiplication that steps downward from n to 1. The product grows very quickly as n increases.
Many calculators have a factorial key written as n! (often accessed via a 2nd/SHIFT function). Enter n, then apply n!.
It’s typically labeled n!. On some calculators it’s a secondary function above a key, so you may need 2nd/SHIFT to access it.
It depends on the model. Look for n! printed on the keypad (often above another function) or in the math/probability menu.
On many TI-30X models, factorial is in a MATH/PRB menu or as n! under a 2nd function. Enter n, then choose n!.
On TI-83/TI-84, factorial is commonly in the MATH menu under PRB. Enter n, then select n!.
Large factorials can exceed normal display limits, so results are often shown in scientific notation to keep them readable.
1000! is an extremely large number with thousands of digits. Calculators typically display it in scientific notation rather than writing every digit.
The standard factorial n! is defined for non-negative integers. Extensions exist (Gamma function), but that’s not the usual “factorial” button on a calculator.