Question

What The Difference Between
nCr & nPr
What I'm Asking Is What Is The C & P

Answer 1

Order does or does not matter.

Answer 2

Let's say, pizza toppings for example.

Answer 3

Combination and permutation

Answer 4

Say we have three toppings: Mushrooms, sausages, and pineapples.

Answer 5

Ok.

Answer 6

If we get to pick any of the two toppings, how many diferent pizzas can we order?

Answer 7

The answer is 3C2

Answer 8

The difference between 3C2 and 3P2

Answer 9

is that in combinations, the order doesn't matter. Choose mushrooms and pineapples is the same as choosing pineappples and mushrooms.

Answer 10

And, you might wonder when order does matter.

Answer 11

Perhaps the most common example is in passwords

Answer 12

Say we have a three letter password (Don't do this lol)

Answer 13

Lolz

Answer 14

Now, how many different passwords are there?

Answer 15

It will be 26P3

Answer 16

How many forms you have to chosse 2 ingredients of that three?\[\left(\begin{matrix}3 \\ 2\end{matrix}\right)\]

Answer 17

WOW!! Where'd U Get The 26???

Answer 18

btw, what @RaphaelFilgueiras did with LaTex is the another way of expressing 3C2

Answer 19

There are twenty six letters in the alphabet

Answer 20

Now, I forgoet to add something to my password example

Answer 21

Assume that the letters can not be reapeated. THis is very important.

Answer 22

We have, 26 for the first letter, then 25 for the second (because the first is already occupied), and 24 for the third, or 26P3

Answer 23

(On a side note, if you *could* repeat letters, that would be 26*26*26=26^3

Answer 24

Hmmmm Aright I Think I Get In Now, So If It Was 10P4
It Would Go Somethin Like This
10x9x8x7= ?? Rite

Answer 25

Yes,

Answer 26

10C4 would be a little different

Answer 27

it would be (10P4)/(4!)