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COMBINA

The COMBINA 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.

Usage

Use the COMBINA formula with the syntax shown below, it has 2 required parameters:

=COMBINA(n, k)
Parameters:
  1. n (required):
    The total number of items in the set.
  2. 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 the COMBINA 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 4-digit passwords that can be formed using the digits 0-9, 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 non-numeric 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. Double-check 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, and k, 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.