What's the difference between permutations and combinations?

Permutations count arrangements where order matters; combinations count selections where order does not matter.

Permutation & Combination Calculator

Given a total number of items n and a selection size r, calculate the number of permutations and combinations possible.

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Formula

nPr = n! / (n−r)!, nCr = n! / (r!(n−r)!)

GCD, LCM, Permutations, and Combinations Explained

The Euclidean algorithm behind GCD/LCM, and the factorial math behind permutations and combinations.

GCD & LCM Calculator

Find the greatest common divisor and least common multiple of two numbers.

Percentage Calculator

Find what percentage one number is of another, or calculate percentage change.

Percentage Change Calculator

Calculate the percentage increase or decrease between two values.

Quadratic Equation Solver

Solve ax² + bx + c = 0 for real roots using the quadratic formula.

Average (Mean) Calculator

Calculate the average of up to 10 numbers.

Standard Deviation Calculator

Calculate the population standard deviation of up to 5 numbers.