Arranjo Simples A(n,k)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
A(n,k) = n!/(n−k)!
About this calculator
The Simple Arrangement A(n,k) calculator determines the number of ways to choose and order k distinct elements from a set of n elements, where order matters and there is no repetition. The calculation uses the formula A(n,k) = n! / (n−k)!, which counts all possible sequences without repeating elements. For example, when choosing 3 letters from a 5-letter alphabet, the simple arrangement shows how many different 3-letter passwords can be formed, considering that the order of letters changes the result.
The operation is based on the fundamental counting principle: for the first element, there are n options; for the second, n−1; and so on until the k-th element, with n−k+1 options. The product of these terms equals n!/(n−k)!. The tool automates this calculation, avoiding manual errors and providing the result instantly. Simply enter the values of n (total elements) and k (chosen quantity), with n ≥ k ≥ 0.
This calculator is useful in situations such as creating passwords, forming queues, work schedules, or any context where the order of elements is relevant. For example, when defining a committee of 3 distinct positions (president, vice president, and secretary) from 10 candidates, the simple arrangement calculates how many different formations are possible. It is also applied in probability and statistics to calculate ordered sample spaces.
Important precautions: ensure n and k are non-negative integers and that n ≥ k. The order of elements matters; if order does not matter, use combination. Remember that the simple arrangement does not allow element repetition. For repetition, use arrangement with repetition. Also check whether the problem considers all elements distinct; otherwise, adjust the formula.
Frequently asked questions
What is the difference between simple arrangement and combination?
In simple arrangement, the order of elements matters; in combination, order does not matter. For example, choosing 3 people for different positions (president, vice, secretary) is an arrangement; choosing 3 people for a group without roles is a combination.
Can I use n and k equal?
Yes, when n = k, the simple arrangement equals n! (permutation of n elements), because you are ordering all elements.
What if n is less than k?
It is not possible to calculate a simple arrangement because there are not enough elements to choose k distinct ones. The calculator will return an error or zero.
How to calculate arrangement with repetition?
Arrangement with repetition allows repeated elements and uses the formula n^k. For that, use the arrangement with repetition calculator.
Is simple arrangement used in lotteries?
Not directly, because in lotteries the order usually does not matter (combination is used). However, it can be used in games where the order of drawn numbers matters.