Combinations with repetition

Find out how many different ways you can choose k items from n items set. With/without repetition, with/without order.

Calculation:

C_{k}^{'} (n) = (\binom{n + k - 1}{k}) n = 11 k = 3 C_{3}^{'} (11) = C_{3} (11 + 3 - 1) = C_{3} (13) = (\binom{13}{3}) = \frac{13!}{3! (13 - 3)!} = \frac{13 \cdot 12 \cdot 11}{3 \cdot 2 \cdot 1} = 286