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Factorial Calculator

Last updated: June 2026

Factorials Calculator

Enter a non-negative integer (up to 3,000) to find the product of all integers down to 1.

Note: Factorials grow extremely fast. n > 1500 may take a split second.
Presets:

Result

10! Result
3628800
Scientific Notation
3.62880 × 10^6
Digits
7

Repeated Multiplication

10! = 10 × 9 × 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1 = 3628800

Word Arrangement Solver (Permutations with Duplicates)

Arrange the letters in a word. If there are duplicate letters, the result is divided by the factorials of the duplicate letter counts:
Formula: n! / (d₁! × d₂! × …)

Workings for "physics"
• Total Letters (n): 7 (7!)
• Duplicates: s: 2 (2!)
• Calculation: 7! / (2!)
• Total Ways: 2,520

What is a Factorial?

A factorial is a mathematical function that multiplies a positive integer by every positive integer smaller than itself. It is denoted by the exclamation point symbol (!). For example, 5 factorial (written as 5!) is:
5! = 5 × 4 × 3 × 2 × 1 = 120.

Arranging Objects

Factorials are standard in combinatorics. There are exactly n! ways of arranging n unique items in an ordered sequence.

Definition of 0! = 1

By definition, 0! = 1. This ensures algebraic consistency in permutation formulas where nPr = n! / (n − r)! when n = r.

💡 Permutations ExampleHow many ways can the letters of the word "document" be arranged?
Since there are 8 letters and all are unique, the number of ways is 8! = 40,320.
For words with duplicate letters (like "physics" with two 's' letters), divide by duplicates' count factorial: 7! / 2! = 2,520.

Calculate the factorial of any non-negative integer n! up to 3,000, displaying the full long integer and scientific notation.

The Factorial Calculator is a specialized combinatorics tool designed to calculate the factorial of any non-negative integer. In mathematics, the factorial of a positive integer n, denoted by n!, is the product of all positive integers less than or equal to n. For example, the factorial of 5 (5!) is calculated as 5 × 4 × 3 × 2 × 1 = 120. By mathematical definition, the factorial of zero is equal to one (0! = 1), representing the single empty set arrangement. Factorials are fundamental to combinatorics, probability theory, algebra, and calculus.

The values of factorials grow extremely rapidly, a phenomenon known as exponential growth. For example, 10! is 3,628,800, and 20! is over 2.4 quintillion. Because of this massive scale, standard floating-point calculators quickly run into overflow errors when evaluating factorials of relatively small integers. This calculator utilizes BigInt representations to handle computations for larger integers without losing precision, allowing users to calculate factorials up to 170! exactly.

In advanced mathematics, the concept of factorials is extended to non-integers (real and complex numbers) using the Gamma Function, defined by Leonhard Euler. The Gamma Function is written as Γ(n) = (n−1)!, serving as a continuous curve that connects factorial points on a graph. Factorials are crucial for binomial expansions, calculating permutations and combinations, evaluating Taylor series approximations for trigonometric and exponential functions, and modeling statistical distributions. By providing fast, exact results, the factorial calculator is an indispensable utility for algebra homework, statistical modeling, and combinatorics calculations.

How it Works & Formula

n! = n × (n − 1) × (n − 2) × … × 1

Computes factorials of positive integers. By definition, 0! = 1.

Practical Examples

Example 1: Factorial of 5

5! = 5 × 4 × 3 × 2 × 1 = 120.

Frequently Asked Questions

Can you calculate factorials for non-integers?

Yes, using the Gamma function, which extends the factorial concept to all real and complex numbers.