Arrangements and permutations calculator

Choose how many distinct elements to arrange and get every digit of the answer.

Distinct elements n
Positions to fill k

Ordered selections A(10, 3)

720

Digits in the result: 3

Contents

How the calculator counts different orders

Three distinct tokens placed in two different orders

Choose how many distinct elements exist and how many positions you will fill. The calculator counts each different order as a new outcome. Its full-permutation mode uses every element, so it needs only the total.

Choose the mode by the number of positions

Use an ordered selection when only k of n elements take positions. For first, second and third place among ten runners, changing the runner in any one place changes the result. A full permutation arranges all n elements, such as placing five different books along a shelf.

A(n,k)=n!(nโˆ’k)!,P(n)=n!A(n,k)=\frac{n!}{(n-k)!},\qquad P(n)=n!

The exclamation mark means factorial: multiply all positive integers down to 1. The calculator instead multiplies only the needed factors for an ordered selection. It uses exact integers, even when the answer has thousands of digits.

What the number represents

Ten runners can fill three prize positions in A(10, 3) = 10 ร— 9 ร— 8 = 720 ways. Swapping two winners creates a different podium, so order matters.

Five different books can fill all five shelf positions in P(5) = 120 ways. Selecting just two books and deciding which goes first would instead give A(5, 2) = 20.

Eight proposals can fill the first two presentation slots in A(8, 2) = 56 ways. Choosing two proposals without deciding their slots would give only C(8, 2) = 28 combinations.

Drawing five cards in sequence from a 52-card deck produces A(52, 5) = 311,875,200 different orders. A five-card hand ignores that sequence, so its count is much smaller.

No reuse, no rounding

The elements must be distinct and cannot be reused. If a code permits the same symbol in several places, this calculator's answer will be too small. For zero filled positions, A(n, 0) = 1: there is one empty order. Likewise P(0) = 1.

Enter whole numbers from 0 through 3,000, with k no greater than n. Grouping spaces make long answers readable; copying returns the same exact integer without spaces. The limit controls output size rather than changing the mathematics.

Questions before choosing a formula

The important choice is whether positions are different and whether an element may appear more than once.

How is a permutation different from an ordered selection?

A full permutation orders all n distinct elements. An ordered selection fills only k positions, where k can be smaller than n.

When should I use combinations?

Use combinations when swapping selected elements does not change the outcome. Ordered selections distinguish those orders.

Why does choosing zero elements give 1?

There is exactly one empty arrangement. That is the value of the empty product in the formula.

Can a symbol appear twice?

No. Each input element can be used only once; arrangements with repetition need a different calculation.

Are very large answers approximated?

No. The calculator uses exact integer arithmetic and keeps every digit up to the input limit.

What if k equals n?

Then the ordered selection uses the entire set and gives the same answer as a full permutation: A(n, n) = P(n).

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