# Thread: Combination Question

1. ## Combination Question

I am trying to figure out the number of possible combinations which I can arrange this sequence:

123456
where:
4 can also be X
5 can also be Y
6 can also be Z

For example, 1 combination can be:
12345Z

Is the proper equation combinations = (n^n) -1
where n is the number of variables that can be change?

For my example I think think the number of combinations would be 8
(3^3) -1

Thanks for any help!
Mr. EKO

2. Originally Posted by MrEKO
I am trying to figure out the number of possible combinations which I can arrange this sequence:

123456
where:
4 can also be X
5 can also be Y
6 can also be Z

For example, 1 combination can be:
12345Z

Is the proper equation combinations = (n^n) -1
where n is the number of variables that can be change?

For my example I think think the number of combinations would be 8
(3^3) -1

Thanks for any help!
Mr. EKO
You will need to explain this more clearly.

Is 231ZX a permitted combination for example?

RonL

3. No, they must be in order

12345Z
1234Y6
1234YZ

etc.

Thank you.

4. Originally Posted by MrEKO
I am trying to figure out the number of possible combinations which I can arrange this sequence:

123456
where:
4 can also be X
5 can also be Y
6 can also be Z
I understand the question as,
123 _ _ _
Where it must be starting as 123.
And for the blank ones we can have,
(4,X) then (5,Y) then (6,Z)
For each space we have 2 possibilities.
Thus in total we have,
(2)(2)(2)=8

5. Thank you.

I assume if I had four spots where it could be changed to a letter it would be
(2)(2)(2)(2) = 16 possible combinations?

6. Originally Posted by MrEKO
Thank you.

I assume if I had four spots where it could be changed to a letter it would be
(2)(2)(2)(2) = 16 possible combinations?
Yes.