Question

Does anyone know how to compute 28P7?? 0.o

Answer 1

In fact, there is a formula for nPr, it goes :
\[\Large _nP_r = \frac{n!}{(n-r)!}\]

Answer 2

But the layman's definition would probably more along the lines of...
\[\Large _{28}P_7 = 28\cdot 27 \cdot ... [\text{until you have a total of 7 factors}]\]

Answer 3

so it would be 28!/(28-7)! ???

Answer 4

Yes, on the whole... yes :D

Answer 5

Which is 28!/21! ??? Right?

Answer 6

Yep.

Answer 7

Ohhhhh ok I get it so the final answer is going to be really long lol

Answer 8

yup... don't be surprised if you get ridiculously large numbers when dealing with these permutation types...

Answer 9

Ok so bear with me on this one. It would be (28 x 27 x 26 x 25 x 24 x 23 x 22 x 21!) (21!)

Answer 10

28 x 27 x 26 x 25 x 24 x 23 x 22

Answer 11

You missed a slash /
You seriously don't want that number to be bigger than it should be, it'd blow up your calculator...
but, it's right :D

Answer 12

WHICH ISSSSSSSSSS 5967561600!!!!

Answer 13

Did you notice that that's exactly how I described it?
28 x 27 x ... until you have 7 factors?
28 x 27 x 26 x 25 x 24 x 23 x 22
--> 7 factors :P

Answer 14

Yeah your way was way easier lol thanks bro

Answer 15

No problem ^_^
The name's TJ by the way :D

Answer 16

Thanks TJ