COMBINA
Returns the number of combinations with repetitions for a given number of items: C(n+k-1, k). Use COMBIN if repetitions are not allowed.
COMBINA(number, number_chosen)Arguments
numberThe total number of items (must be ≥ 0).number_chosenThe number of items chosen (must be ≥ 0).
=COMBINA(4,3)C(6,3) = 20 ways to pick 3 from 4 with repetition
=COMBINA(10,3)C(12,3) = 220 multi-combinations
- •Available since Excel 2013
- •Returns #NUM! if either argument is negative
- •Equivalent to (n+k-1)! / (k!·(n-1)!)
- •Confusing COMBINA with COMBIN - COMBINA allows the same item to be chosen more than once (combinations with repetition), while COMBIN assumes each item can only be selected once
- •Expecting COMBINA and COMBIN to give the same result for the same inputs - they answer genuinely different counting questions and will usually produce very different numbers
- •Passing a negative number to either argument, which returns a #NUM! error since combinations with repetition are only defined for non-negative counts
COMBINCounts combinations without repetition, the more restrictive counting scenario that COMBINA generalizes by allowing repeated selections.PERMUTATIONACounts arrangements with repetition where order matters, a related but distinct scenario from COMBINA's order-independent, repetition-allowed counting.FACTUsed internally in the mathematical formula behind COMBINA, since combinations with repetition are calculated using factorials.What's the difference between COMBINA and COMBIN?
COMBINA allows the same item to be chosen multiple times when forming a group (combinations with repetition), while COMBIN assumes each item can only be selected once. They answer different questions and give different results for the same inputs.
Why does COMBINA return a #NUM! error?
One of the arguments is negative - both number and number_chosen must be zero or greater for combinations with repetition to be defined.
When would I use COMBINA instead of COMBIN?
Use COMBINA when items can be selected more than once, like counting the ways to choose scoops of ice cream from a set of flavors where repeats are allowed - COMBIN would undercount that scenario.
Need to translate a formula using COMBINA?
Use our translator to convert your complete formula