If you want to calculate ${}_nC_r=\frac {n!}{r!(n-r)!}$, use the nCr button. If you want to calculate ${}_nP_r=\frac {n!}{(n-r)!}$, use the nPr button. It is my strong belief that you should not be …

$\begingroup$ For nCr, you can always explain drafting potential athletes for your team, out of a fixed pool. For nPr, you can explain the same thing, only the order matters, since you're …

Nov 17, 2015 · I have a test tomorrow in statistics and was wondering what the following means? $$\binom{50}{4}$$ My professor along with most of my classmates have a calculator they can …

Dec 28, 2015 · Stack Exchange Network. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for …

I have a very simple question. Could someone elaborate on the notation of two numbers stacked inside brackets? Such as: $$ \\begin{pmatrix} 5 \\\\ 1 \\\\ \\end{pmatrix} $$

Dec 11, 2019 · $\begingroup$ Hello, what your paper states is a generalized formula for nCr as a series. But what I am asking for is a formula for the summation of nCr with r ranging from a to …

Sep 23, 2019 · I remember watching this video on the proof behind the nCr factorials and I understood the logical proof clearly. However, I remember when asked. Expand $(x+y)^3$ I …

Aug 30, 2017 · Okay, so I'm designing a calculator that accepts real and imaginary inputs, and I'm going to implement the nPr and nCr functions soon. I already programmed in the factorial …

Jun 9, 2016 · First, because there are 13 sets of four-of-a-kind, number of ways of selecting one of the 13 ranks is $\begin{pmatrix}13\\1\end{pmatrix}$ Then, once you have chosen the rank, …

Sep 20, 2017 · There was a previous problem in my homework that basically demonstrated that: 10C7 = 9C6 + 8C6 + 7C6 + 6C6 And our question is: "Use that fact to derive a summation …