COMBINA

The COMBINA function returns the number of combinations for a given number of items. A combination is a group of items where order does not matter. There are two kinds of combinations: The COMBINA function allows repetitions. To count combinations that do not allow repetitions, use the COMBIN function. To count permutations (combinations where order does matter) see the PERMUT function. A good real-world example is ordering a 3-scoop ice cream cone from 10 flavors: order does not matter and you can repeat flavors (three scoops of chocolate is fine), so this is a combination with repetition. For a full explanation, see Combinations and permutations in Excel. The COMBINA function takes two arguments: number, and number_chosen. Number is the number of different items available to choose from.