Mathematics · Glossary
What is Permutation?
Quick definition
An arrangement of items in a specific order. Number of ways to arrange n items = n! (n factorial).
Full explanation
A permutation is an ordered arrangement of items. The number of permutations of n distinct items is n! (n factorial = n×(n-1)×(n-1)...×1). For example, 3! = 6 ways to arrange 3 items. Permutations of n items taken k at a time is n! / (n-k)!. Permutations are used in probability, cryptography, scheduling, and rank calculations. They differ from combinations: in a permutation, ORDER matters (AB ≠ BA); in a combination, order does not. "How many ways to arrange 5 people in a line" = 5! = 120. "How many 3-person committees from 10 people" = 10C3 = 120 — a combination.
Related calculators
Calculators that use or explain Permutation.
Related terms
More from Mathematics
Standard Deviation
A measure of how spread out numbers are from their mean. Low = consistent, high = volatile.
P-Value
The probability of observing results at least as extreme as those observed, assuming the null hypothesis is true.
Mean (Average)
The sum of values divided by the count. The most common type of "average." Sensitive to outliers.
Median
The middle value in a sorted list. Half the values are above, half below. Robust to outliers.
Pythagorean Theorem
In a right triangle, the square of the hypotenuse equals the sum of the squares of the two legs: a² + b² = c².
Logarithm
The exponent to which a base must be raised to produce a given number. log(100) = 2 means 10² = 100.
Last reviewed: June 15, 2026 • Category: Mathematics