If we need to find how many combinations we can make from n items when we have r positions and allow repetition we can apply the following formula:
(r+n-1)!/(r!(n-1)!)
Is there any formula to calculate the number of combinations when the number of repetition for each item is limited? Namely, if we had 2 items s1 and s2 and We can use s1 x times and s2 y times. We have r positions how many combinations of those items We can make?
For example if s1 can be used 2 times ,s2 can be used 2 times as well and r = 2. The number of combinations is equal to 3 = {s1,s1} {s1, s2}, {s2,s2}
(r+n-1)!/(r!(n-1)!)
Is there any formula to calculate the number of combinations when the number of repetition for each item is limited? Namely, if we had 2 items s1 and s2 and We can use s1 x times and s2 y times. We have r positions how many combinations of those items We can make?
For example if s1 can be used 2 times ,s2 can be used 2 times as well and r = 2. The number of combinations is equal to 3 = {s1,s1} {s1, s2}, {s2,s2}