Permutations & combinations (1 Viewer)

[EY]

Can somebody please tell me what the ! means?

 

[withoutaface]

n!= n*(n-1)*(n-2)*...*3*2*1

 

[thunderdax]

It means find the product of that number and every positive integer less than itself.

 

[wanton-wonton]

0! = 1, by convention/definition.
1! = 1
2! = 2*1 = 2
3! = 3*2*1 = 6
4! = 4*3*2*1 = 24

I hope you can see a pattern.

 

[EY]

nope... it's not happening

 

[rama_v]

nope... it's not happening

the ! just means 'factorial' so 2! is 2 factorial..the meaning of 'factorial' has already been described above

 

[David_O]

Try this then:
0! = 1
n! = n times (n-1)!

So:
1! = 1 times 0! = 1*1 = 1
2! = 2 times 1! = 2*1 = 2
3! = 3 times 2! = 3*2 = 6
and so on...

 

[king_of_boredom]

nope... it's not happening

...ok then, for example,

4! = 4 x 3 x 2 x 1

4! = four factorial.

It means find the product of that number and every positive integer less than itself.

couldn't have said it better myself.