# Are there examples where mathematicians needs to calculate big combinations

With the $C_n^k$ formula, I managed to optimize it for finding very big numbers such as $C_{7130}^{7125}$ rather quickly. I could have used GMP or Ruby because unsigned long don't hold a lot of values, but here is my question:

Are there applications where people need to compute such numbers ? Because the plain factorial methods can be quite long compared to my method...

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Have you already checked your formula/algorithm against those provided by most mathematical programming packages? (Matlab, Mathematica, R, etc...) – Raskolnikov Apr 22 '11 at 12:44
...or this one, which is similar: numbertheory.org/php/binomial.html – Hans Lundmark Apr 22 '11 at 17:51

some_int_type nCr = 1 ;