This Combinations with Replacement Calculator can help you calculate the value for CR(n,r) = C(n+r-1,r) = (n+r-1)!/r!(n – 1)!, where both n and r should be >= 0.
Combinations with replacement formula
The combinations with replacement are by convention denoted by CR(n,r):
Initial notation: CR(n,r) = C(n + r - 1,r)
Intermediary form: CR(n,r) = (n + r - 1)! / r! (n + r - 1 - r)!
Final formula: CR(n,r) = (n + r - 1)! / r! (n - 1)!
n = the number of possibilities
r = items to be picked up at once
! – is the factorial symbol
both “r” and “n” should be equal or greater than 0.12 Aug, 2015