Question 1130818
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You have received two good responses showing the calculation based on the definition of nCr.<br>
If you have to do a lot of calculations of nCr numbers, you will be wasting a lot of time if you go back to the definition of nCr every time.<br>
The expression to evaluate nCr is a fraction with a product of r numbers in both numerator and denominator; the numbers in the numerator start with n and count down; the numbers in the denominator start with r and count down.<br>
A couple of examples....<br>
7C3 = {{{(7*6*5)/(3*2*1)}}}<br>
10C4 = {{{(10*9*8*7)/(4*3*2*1)}}}<br>
So for your example,<br>
35C2 = {{{(35*34)/(2*1) = 35*17 = 595}}}