COMBINA
TheCOMBINA
function calculates the number of combinations with repetitions of k items taken from a set of n items. This function is useful when you want to calculate the number of possible combinations that can be formed by selecting k items from a set of n items, where repetition of items is allowed.
 How to use
COMBINA
formula?  Examples of using
COMBINA
formula COMBINA
formula not working? Similar formulas to
COMBINA
Usage
Use the COMBINA
formula with the syntax shown below, it has 2 required parameters:
 n (required):
The total number of items in the set.  k (required):
The number of items to be selected from the set.
Examples
Here are a few example use cases that explain how to use theCOMBINA
formula in Google Sheets.
Calculating the number of possible outcomes
Suppose you want to calculate the number of possible outcomes of a lottery game where a player selects 5 numbers out of 40. You can use the COMBINA
function to calculate the total number of possible combinations that can be formed by selecting 5 numbers from a set of 40, where repetition of numbers is allowed.
Calculating the number of unique combinations
Suppose you want to calculate the number of unique combinations of 3 letters that can be formed from the set {A, B, C, D, E}, where repetition of letters is allowed. You can use the COMBINA
function to calculate the total number of possible combinations and subtract the number of repeated combinations.
Calculating the number of possible passwords
Suppose you want to calculate the number of possible 4digit passwords that can be formed using the digits 09, where repetition of digits is allowed. You can use the COMBINA
function to calculate the total number of possible combinations and subtract the number of repeated combinations.
Common Mistakes
COMBINA
not working? Here are some common mistakes people make when using the COMBINA
Google Sheets Formula:
Incorrect Syntax
Users often forget to include both arguments in the formula or use incorrect syntax, resulting in an error. Ensure that both n and k are included in the formula and separated by a comma.
Invalid Arguments
Users sometimes include nonnumeric or negative values for n and/or k, which will result in an error. Ensure that both n and k are positive integers.
Incorrect Result
Users may not realize that COMBINA calculates the number of combinations with repetition, not without repetition. Doublecheck that the result makes sense for the intended purpose.
Related Formulas
The following functions are similar to COMBINA
or are often used with it in a formula:

COMBIN
The
COMBIN
function calculates the number of combinations for a given number of items. A combination is a way of selecting items from a larger set where order does not matter. This function is commonly used in probability and statistics. 
PERMUT
The
PERMUT
function returns the number of permutations of a set of objects. A permutation is a way of arranging objects in a specific order. The function takes two arguments:n
, the total number of objects, andk
, the number of objects to arrange. The result is the number of possible permutations. This function is commonly used in combinatorics and probability theory. 
FACT
The
FACT
formula calculates the factorial of a given number. The factorial of a number is the product of all positive integers from 1 to the given number. This formula is commonly used in probability and combinatorics. 
BINOMDIST
The
BINOMDIST
function calculates the probability of a certain number of successes in a fixed number of trials given a constant probability of success for each trial. This function is commonly used in statistical analysis and hypothesis testing.
Learn More
You can learn more about the COMBINA
Google Sheets function on Google Support.