Calculating Individual Factorials
A factorial, denoted as n!, is a mathematical operation that multiplies a given number n by all positive integers less than itself. This concept is fundamental in combinatorics and various fields of mathematics and computer science. The factorial of a non-negative integer n can be defined recursively or iteratively.
Definition
Formally, the factorial of n is given by:
n!={1n×(n−1)×(n−2)×⋯×1if n=0if n>0
Examples
- The factorial of 5 (5!) is:
5!=5×4×3×2×1=120
- The factorial of 0 (0!) is defined as 1 by convention.
Properties
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Growth Rate: Factorials grow exponentially. For large n, n! becomes very large, very quickly.
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Recursive Definition:
n!=n×(n−1)!
Usage in Permutations and Combinations
Factorials are crucial in calculating permutations and combinations in probability and statistics. For instance, the number of ways to arrange n distinct objects is n!.
Implementation
Recursively:
factorial(n)={1n×factorial(n−1)if n=0if n>0
Iteratively:
factorial=1for i in range(1, n+1): factorial∗=i
Understanding and calculating factorials is essential for solving many mathematical problems and performing specific computational tasks efficiently.