Factorial Calculator
Calculate factorials with step-by-step breakdown and large number support.
About this tool
A factorial is a fundamental mathematical operation where you multiply a number by every positive integer below it. The factorial of 5, written as 5!, equals 5 × 4 × 3 × 2 × 1 = 120. This simple operation has surprisingly deep applications across mathematics, computer science, and probability. Factorials describe how many ways you can arrange a set of objects, how many combinations are possible, and they even appear in calculus and advanced functions.
Using this calculator is straightforward: enter any whole number from 0 to 100 and instantly see the exact result. What makes this tool special is that it handles large factorials correctly—beyond 20, regular JavaScript numbers lose precision, but this calculator uses string-based multiplication to compute the exact value every time. You'll see the full step-by-step breakdown showing each multiplication, making it easy to understand how the result grows.
This calculator is useful for students learning combinatorics, professionals working with probability calculations, and anyone curious about how quickly numbers can grow. Whether you're solving permutation problems, calculating odds, or exploring number theory, having a reliable tool that shows the complete process helps build understanding and catch mistakes early.
Frequently Asked Questions
Code Implementation
import math
# Built-in factorial
print(math.factorial(10)) # 3628800
print(math.factorial(50)) # exact large integer
print(math.factorial(100)) # 158-digit number
# Manual implementation
def factorial(n):
if n == 0: return 1
result = 1
for i in range(2, n + 1):
result *= i
return result
# Step-by-step display
n = 5
steps = " × ".join(str(i) for i in range(n, 0, -1))
print(f"{n}! = {steps} = {factorial(n)}")Comments & Feedback
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