Question

Calculate the result of the following formula: P(14,7) Don't want the answer, just don't understand how to solve.

Answer 1

\[\rm P(n, r) = \dfrac{n!}{(n-r)!}\]

Answer 2

\[\rm P(14, 7) = \dfrac{14!}{(14-7)!}\]

Answer 3

do you know how to work a factorial ?

Answer 4

We eliminate the the overlapping numbers to reduce the work I think...

Answer 5

14*13*12...*3*2*1

Answer 6

yes!

Answer 7

The number seems awfully large which is throwing me for a loop.

Answer 8

\[\rm P(14, 7) = \dfrac{14!}{(14-7)!}= \dfrac{14!}{7!}\\\]

Answer 9

\[ = \dfrac{14\times 13\times 12\times 11\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1}{7\times 6\times 5\times 4\times 3\times 2\times 1}\]

Answer 10

\[\require{cancel} = \dfrac{14\times 13\times 12\times 11\times 10\times 9\times 8\times \cancel{7\times 6\times 5\times 4\times 3\times 2\times 1}}{\cancel{7\times 6\times 5\times 4\times 3\times 2\times 1}^1}\]

Answer 11

Ohhhhhh!!!!!

Answer 12

I KNEW there was some sort of elimination process.

Answer 13

\[=14\times 13\times 12\times 11\times 10\times 9\times 8 \]

Answer 14

:) you still need use your calculator ^

Answer 15

Yea, it's still a giant number.

Answer 16

So I have this oversized number. What's to be done with it now?

Answer 17

you're done, thats the value of P(14, 7)

Answer 18

p(14,7)=121080960

Answer 19

That just seems...excessive.

Answer 20

http://www.wolframalpha.com/input/?i=P%2814%2C7%29

Answer 21

How'd I goof THAT up...

Answer 22

looks you have multiplied by 7

Answer 23

you should stop at 8

Answer 24

Yep. Spot on. Do you, by chance, know the name of that formula?

Answer 25

P(14,7) = 14x13x12x11x10x9x8

Answer 26

permutation formula

Answer 27

You're top notch. Thanks so much for help! I have a much better grasp on these sort of equations and that formula.

Answer 28

you're welcome :)