# A to Z of Excel Functions: the COMBINA Function

4 September 2017

*Welcome back to our regular A to Z of Excel Functions blog. Today we look at the COMBINA function. *

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**The COMBINA function**

This function returns the number of combinations (with repetitions) for a given number of items. If this sounds a little confusing, think of it this way: you have a **number **of balls in the bag, each with a different number on it. You take one ball out at random, record its number, then replace it. You do this **number_chosen** times. Ignoring the sequence of the numbers selected, **COMBINA** deduces the number of different combinations. Since there is replacement, **number_chosen** may exceed the **number** too.

For example the selecting three numbers from a bag of balls numbered 1 to 4 would have the following 20 combinations:

111, 112, 113, 114, 122, 123, 124, 133, 134, 144, 222, 223, 224, 233, 234, 244, 333, 334, 344 and 444.

The **COMBINA **function employs the following syntax to operate:

**COMBINA(number, number_chosen)**

The **COMBINA** function has the following arguments:

**number****:**this is required and must be greater than or equal to zero. Microsoft states that**number**must be**number_chosen**but this requirement does not seem to hold in practice (see my examples below)**number_chosen:**this is also required and Must be greater than or equal to zero too**n**on-integer values for both arguments will be truncated.

It should be further noted that:

- If the value of either argument is outside of its constraints,
**COMBINA**returns the*#NUM!*error value - If either argument is a non-numeric value,
**COMBINA**returns the*#VALUE!*error value - The following equation is used:

- In the equation above,
**N**is**number**and**M**is**number_chosen**.

Please see my examples below:

*We’ll continue our A to Z of Excel Functions soon. Keep checking back – there’s a new blog post every other business day.*

*A full page of the function articles can be found here. *