Then a comma and a list of items separated by commas. Note that AB and BA are considered to be one combination because the order in which objects are selected does not matter. So some of the permutations would be ABC ACB BAC BCA CAB and CBA.
This is the key distinction between a combination and a permutation.
The formula show us the number of ways a sample of r elements can be obtained from a larger set of n distinguishable objects where order does not matter and repetitions are not allowed. To calculate combinations we will use the formula n C r n. Mega Millions players must choose five numbers from 1 to 70 and one Mega Ball from 1 to 25. The number of k-combinations for all k is the number of subsets of a set of n elements.