# Combination Formula

The combination formula describes the possible combination r elements out of a group of n elements where order does not matter.

## Example

If we have four animals the possible combinations of four choose three is:

The set of four animals:

{🦕,🐓,🦎,🐟}

There are four possible combinations of four choose three.

- {🦕,🐓,🦎}
- {🦕,🐓,🐟}
- {🦕,🦎,🐟}
- {🐓,🦎,🐟}

Note that the order does not matter. The set {🦕,🐓,🦎} is viewed the same as {🐓,🦕,🦎}

## Example

This example shows the possible combinations of four choose two using the combination formula.

The set of four animals:

{🐢,🐥,🐖,🐋}

The are six possible combinations of four choose two.

- {🐢,🐥}
- {🐢,🐖}
- {🐢,🐋}
- {🐥,🐖}
- {🐥,🐋}
- {🐖,🐋}