Factorial Calculator
n! = 1×2×3×...×n
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Pro Tip
Stirling's approximation: n! ≈ √(2πn) × (n/e)ⁿ. For large n, this is very accurate. For n=10: exact = 3,628,800; Stirling gives 3,598,696 (0.83% error).
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Did you know?
The number of ways to shuffle a standard 52-card deck is 52! ≈ 8 × 10⁶⁷. This number is so large that every time you shuffle a deck, you are almost certainly creating an ordering that has never existed before in human history.
📖Difficulty:Intermediate
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Variable Legend
n= non-negative integern!= factorial of n
Definition
Product of all positive integers from 1 to n.
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Base case
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Recursive definition
Each factorial is n times the previous.
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Stirling's approximation
Accurate estimate for large n.
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n= non-negative integer
n!= factorial of n
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