# How do we Understand Permutation and Combination?

The science of counting objects according to specific rules and concepts is studied under a separate discipline, combinatorics. This involves “issues of selection, organisation, and operation within a finite or discrete system,” and sometimes also known as “Combinatorial Mathematics” or “Permutation and Combination”.

The goal of this branch is to learn how to count without actually counting. The combinations and permutations are the two fundamental approaches that identify the number of potential configurations of objects of a particular kind.

## Given below is a brief understanding of permutations and combinations and the number of ways in which they are similar and different.

## What are Permutations

A permutation is a concept that describes any of the possible arrangements that may be created by taking any few or all of the items from the given set. However, in order to explain permutations mathematically, we would say a permutation is a collection of **n** items that are taken at **r** time, in a specified sequence, with no repeat.

## Types of Permutations

The permutations may further divided into two distinct types: the permutations with repetition and without repetition.

With Repetition Permutation

**How to Calculate Permutations**

There isn’t much complex notion which we use to calculate the permutations. It may calculate by using the permutation formula

**nPr = n! / (n−r)!**

In permutation, we will calculate the ratio from the factorial of a total number of things to the factorial difference between the number of items available and choose.

But such calculation can also perform by using advanced tools for mathematics. By using permutation calc, you may be able to calculate the exact or unique sequence of digits or numbers.

**What are Combinations**

A combination is a group of several things that we are arranging without any sequence in it.

Keep in mind that combinations do not lay emphasis on order, positioning, or arrangement, but rather on the individual pieces that make up the combination.

**How to Calculate Combinations**

The method for determining the number of combinations is the same as the formula for calculating the number of permutations, albeit with one addition: when dividing by **n!** the **r!** is inserted in the equation as well.

Thus when **n **objects are combined, the number of possible combinations is counted **r** at a time using the formula

**nCr = n! / (n-r)! r!**

Similar to the permutation calculator, there is also an advanced tool through which one should calculate the combination to determine the way in which we can possibly arrange the numbers.

**Similarities between Permutations and Combination**

Combination and permutation are two different concepts that are connecting to one another. Both are the concepts of combinatorics, the subfield of mathematics concerned with the finite and countable discrete structures study.

When it comes to mathematics, permutations and combinations are two terms that relate to alternative ways of organising a particular collection of objects. As described, combinations are the process of counting the number of selections we make from a set of **n **items. Permutation, on the other hand, is the process of calculating the number of arrangements that may be made from **n **items.

**Differences between Permutations and Combination**

We know these concepts of permutation and combination have a relation. Yet they also differ from one another, the general differences are:

If you choose items in a combination, the order in which they appear is unimportant; nevertheless, in a permutation, the order is critical.

- In combination, we have only made a selection. But in a permutation, an arrangement in a sequence will keep with the selection.
- In a combination, the order of selected objects is immaterial whereas, in a permutation, the order is essential.

Finding the permutations of n distinct objects, one at a time, requires the following procedure: selecting r items from a pool of n items and then arranging them. As a result, the number of permutations generally outnumbers the number of possible combinations.

Each combination corresponds to a large number of different permutations. Consider the following example: the six permutations ABC, ACB, BCA, BAC, CBA, and CAB are all derived from the same combination ABC: ABC.

- To find the permutations of n different items, taken ‘r’ at a time: we first select r items from n items and then arrange them. So usually, the number of permutations exceeds the number of combinations.
- There will selection made in a combination. But in permutation, the definite order with that selection is considerable.
- Each combination corresponds to many permutations. For example, the six permutations ABC, ACB, BCA, BAC, CBA and CAB correspond to the same combination ABC.

So here you read what are the combinations and the permutations in a series of numbers. If we recap our concepts, Permutation are the number of ways to arrange numbers. While on the other hand, combinations are the exact sequence and arrangement which we follow for numbers or digits.