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# ​ Permutations...

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275
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Jul 9, 2017

#1
+7347
+2

You can put it into the calculator on the home page like this:    npr(12,9)

But if you don't have a calculator that can do this.....

$$_nP_r=\frac{n!}{(n-r)!} \\~\\ _{12}P_9=\frac{12!}{(12-9)!} \\~\\ _{12}P_9=\frac{12!}{3!} \\~\\ _{12}P_9=\frac{12\,\cdot\,11\,\cdot\,10\,\cdot\,9\,\cdot\,8\,\cdot\,7\,\cdot\,6\,\cdot\,5\,\cdot\,4\,\cdot\,3!}{3!} \\~\\ _{12}P_9=12\,\cdot\,11\,\cdot\,10\,\cdot\,9\,\cdot\,8\,\cdot\,7\,\cdot\,6\,\cdot\,5\,\cdot\,4 \\~\\ _{12}P_9=79,833,600$$

.
Jul 9, 2017

#1
+7347
+2

You can put it into the calculator on the home page like this:    npr(12,9)

But if you don't have a calculator that can do this.....

$$_nP_r=\frac{n!}{(n-r)!} \\~\\ _{12}P_9=\frac{12!}{(12-9)!} \\~\\ _{12}P_9=\frac{12!}{3!} \\~\\ _{12}P_9=\frac{12\,\cdot\,11\,\cdot\,10\,\cdot\,9\,\cdot\,8\,\cdot\,7\,\cdot\,6\,\cdot\,5\,\cdot\,4\,\cdot\,3!}{3!} \\~\\ _{12}P_9=12\,\cdot\,11\,\cdot\,10\,\cdot\,9\,\cdot\,8\,\cdot\,7\,\cdot\,6\,\cdot\,5\,\cdot\,4 \\~\\ _{12}P_9=79,833,600$$

hectictar Jul 9, 2017