Factorial Calculator

About Factorial Calculator

A powerful factorial calculator supporting standard factorials (n!), double factorials (n!!), and subfactorials (!n / derangements). Handles values from 0! to 170! with standard precision and uses BigInt for exact results up to 10,000!. Shows the step-by-step multiplication expansion, counts the digits in the result, calculates the number of trailing zeros (from factors of 5), and presents Stirling's approximation for large values. Includes educational explanations of combinatorics applications. Essential for math students, probability learners, and competitive programmers.

Factorial Calculator Features

• n! up to 10,000
• BigInt exact results
• Step-by-step expansion
• Trailing zeros count
• Double & sub-factorials