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## #1 2010-09-16 12:51:31

eelety
Member
Registered: 2010-09-16
Posts: 1

### Find the number of Permutations

I have four problems where I have the find the number of permutations.  Could any help me in figuring out these types of algebra problems.  Subject Algebra I, grade 10.

#1.  7P3
#2   7P7
#3.  8P4
#4.  5P0

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## #2 2010-09-16 13:13:13

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Find the number of Permutations

Hi eelety;

Welcome to the forum!

1) 7P3 Take the first number which is 7 and count down by 1, the second number 3 times. Then multiply.

2) 7P7, Take the first number 7 and count down by 1, 7 times. Then multiply.

Now you try 8P4.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #3 2010-09-16 15:16:24

soroban
Member
Registered: 2007-03-09
Posts: 452

### Re: Find the number of Permutations

Edit: That was really stupid! . . . I used the Combination formula is all of these . . . *blush*

. .

.

Last edited by soroban (2010-09-17 05:15:21)

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## #4 2010-09-16 21:36:36

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

### Re: Find the number of Permutations

That's the formula for Combinations, not Permutations. The difference is that with permutations, order is important. This means that, for example, when choosing all the members of a set, there are many ways of doing so instead of just one.

The formula for permutations is:

Why did the vector cross the road?
It wanted to be normal.

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