Factorial Calculator
? Frequently Asked Questions
What is a factorial?
Factorial (n!) is the product of all positive integers up to n. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120. It's used in combinatorics, probability, and algebra.
What's the largest factorial it can calculate?
JavaScript can precisely calculate factorials up to 20! (2,432,902,008,176,640,000). Beyond that, numbers exceed JavaScript's safe integer limit and may need scientific notation or approximation.
Why is 0! equal to 1?
By mathematical convention and definition, 0! = 1. This makes formulas in combinatorics and calculus work consistently. There's exactly one way to arrange zero objects (do nothing), hence 1.
Can it calculate double factorials?
Some advanced calculators support double factorials (n!!) which multiply every other number: 7!! = 7 × 5 × 3 × 1 = 105, and 8!! = 8 × 6 × 4 × 2 = 384.
How are factorials used in real life?
Factorials calculate permutations (arrangements) and combinations. They're used in probability theory, statistics, computer science algorithms, and determining possible outcomes in games and experiments.
Is my data safe and secure?
Yes, absolutely! This tool runs entirely in your browser. All data processing happens locally on your device - nothing is uploaded to our servers. Your files and data never leave your computer, ensuring complete privacy and security.