# What is combination and permutation formula?

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## What is combination and permutation formula?

The formula for permutations and combinations are related as: nCr = nPr/r!

Is combination and combinatorics same?

For example, the arrangements ab and ba are equal in combinations (considered as one arrangement), while in permutations, the arrangements are different. Combinations are studied in combinatorics but are also used in different disciplines, including mathematics and finance.

### How are combinations and permutations similar?

permutations and combinations, the various ways in which objects from a set may be selected, generally without replacement, to form subsets. This selection of subsets is called a permutation when the order of selection is a factor, a combination when order is not a factor.

What is an example of combination?

A combination is a selection of all or part of a set of objects, without regard to the order in which objects are selected. For example, suppose we have a set of three letters: A, B, and C. Each possible selection would be an example of a combination. The complete list of possible selections would be: AB, AC, and BC.

## How do you do combination problems?

Combinations are a way to calculate the total outcomes of an event where order of the outcomes does not matter. To calculate combinations, we will use the formula nCr = n! / r! * (n – r)!, where n represents the total number of items, and r represents the number of items being chosen at a time.

How do you know if its permutation or combination?

When the order doesn’t matter, it is a Combination. When the order does matter it is a Permutation.

### When do you use a permutation instead of a combination?

“724” won’t work, nor will “247”. It has to be exactly 4-7-2. So, in Mathematics we use more precise language: When the order doesn’t matter, it is a Combination. When the order does matter it is a Permutation.

When is the order doesn’t matter it is a permutation?

When the order doesn’t matter, it is a Combination. When the order does matter it is a Permutation. So, we should really call this a “Permutation Lock”! A Permutation is an ordered Combination.

## Are there any permutations where there is no repetition?

Repetition is Allowed: such as the lock above. It could be “333”. No Repetition: for example the first three people in a running race. You can’t be first and second. 1. Permutations with Repetition

What are the permutations of choosing r of something?

More generally: choosing r of something that has n different types, the permutations are: n × n × (r times) (In other words, there are n possibilities for the first choice, THEN there are n possibilites for the second choice, and so on, multplying each time.)