Count of ways to choose r items from n without order—C(n,r) using multiplicative formula.
It returns the binomial coefficient C(n,r) = n! ÷ (r!(n−r)!) using a multiplicative loop with symmetry r ← min(r, n−r) for speed. n must be an integer 0–60; r must satisfy 0 ≤ r ≤ n. The final value is rounded to the nearest integer after floating steps.
This calculator uses plain decimal numbers. If a result looks wrong, check whether you used a comma instead of a dot (or vice versa) where the field expects one.