Question 391385
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*[tex \LARGE \left(n\cr k\right\)] is the number of combinations of *[tex \Large n] things taken *[tex \Large k] at a time and is calculated by *[tex \Large \frac{n!}{k!(n\,-\,k)!}]

So you want:

*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \left(13\cr\ 4\right\)\ =\ \frac{13!}{4!(13\,-\,4)!}]

You can do your own arithmetic.  Hint:

*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \frac{13!}{9!}\ =\ \frac{13\,\cdot\,12\,\cdot\,11\,\cdot\,10\,\cdot\,9!}{9!}\ =\ 13\,\cdot\,12\,\cdot\,11\,\cdot\,10]

John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
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