COMBIN Returns the number of combinations for a given number of items. Use COMBIN to determine the total possible number of groups for a given number of items.
Syntax
COMBIN(number, number_chosen)
Parameters
Number – The number of items.
Number_chosen – The number of items in each combination.
Return Value
Returns the number of combinations for a given number of items.
Reference Data
https://docs.microsoft.com/en-us/dax/dax-function-reference