Your first question may be – What is COMBIN? And your second question is probably – Why would I need to know about it?

COMBIN is a math function in Excel that calculates all the possible unique combinations of a set of numbers.

For example, say you have a group of four people, and you want to know how many different groups of two that you can make out of that four. This is where you would use the COMBIN function.

## COMBIN Function

Excel’s COMBIN function looks like this:

COMBIN(number, number_chosen)

- number = total number
- number_chosen = number in each combination

So, for the example mentioned above of four people total, and the unique number of groups of two, the formula would be:

=COMBIN(4, 2)

And the answer is: 6

Looking at this example further, the four people are: Bob, Mary, Ralph and Daniel. The possible combinations are:

Bob & Mary | Bob & Ralph | Bob & Daniel | Mary & Ralph | Mary & Daniel | Ralph & Daniel |
---|

This example was a simple one. Now imagine that the amount of people has increased to 10, 50, 100, or 200. How many possible combinations do you think can you get from those amounts of people?

The images below shows the formula and the result:

As the number of choices increase, the possible results of unique combinations greatly increases.

## Further Considerations

Only numbers can be used. If a non-numeric argument is used, the function will result in the #VALUE! error.

A #NUM! error will result if you use zero or less as one of the arguments, or if number is less than number_chosen.

## Conclusion

The COMBIN function is probably not a function that you will commonly use. However, when you need to know the possible combinations of numbers, it will be very useful for that purpose.

For further information of the COMBIN function, see the Microsoft article.

If you have any questions or comments on this function, let me know.