I don't think heureka's method will work on very large numbers such as: nC13=153,121,753,939,078,375
There is, however, a method that will work on any n and it goes as follows:
Take the above answer=153,121,753,939,078,375 x 13! =953,492,346,711,122,973,955,200,000
Now, take this huge last number and take the 13th root of it as follows:
953,492,346,711,122,973,955,200,000^(1/13) =118.941. round off this to 119. Then add 13 to it, or
119 + 13 = 132. Now take the average of [119 + 132] / 2 =125.5. Discard the fractional part and keep the integer part or 125, which is answer to n above.
Note: This method will work on ANY n, no matter the size.