# What is the formula for combinations and permutations?

## What is the formula for combinations and permutations?

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

## How do you calculate combinations with combinations?

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.

What is combination and give example?

A reaction in which two or more reactants combine to form a single product is known as a combination reaction. Combination reaction is also known as a synthesis reaction. Examples of combination reaction. 2Na + Cl2 → 2NaCl. C + O2 → CO2.

How to calculate a permutation?

If you have a calculator handy, find the factorial setting and use that to calculate the number of permutations. If you have to solve by hand, remember that, for each factorial, you start with the main number given and then multiply it by the next smallest number, and so For example, you would calculate 10! In the example, you should get 720.

### When do we use permutation or combination?

A permutation is used for the list of data (where the order of the data matters) and the combination is used for a group of data (where the order of data doesn’t matter).

### When to use permutations or combinations?

A permutation is an arrangement, or listing, of objects in which the order is important. In previous lessons, we looked at examples of the number of permutations of n things taken n at a time. Permutation is used when we are counting without replacement and the order matters. If the order does not matter then we can use combinations.

How do you evaluate the permutation?

To evaluate a permutation or combination, follow these steps: On the Home screen, enter n, the total number of items in the set. Press to access the Math Probability menu. Press [2] to evaluate a permutation or press [3] to evaluate a combination. Enter r, the number of items selected from the set, and press [ENTER] to display the result.

25/02/2021