nCr question choosing 1 - 9 from 9 I've been trying to rack my brain for my high school maths to find the right calculation for this but I've come up blank.
I would like to know how many combinations there are of choosing 1-9 items from a set of 9 items.
i.e.
There are 9 ways of selecting 1 item.
There is 1 way of selecting 9 items.
For 2 items you can choose...
1,2
1,3
1,4
1,5
1,6
1,7
1,8
1,9
2,3
2,4
and so on.
How many ways in total are there of selecting any number of items from a set of 9 (without duplicates, i.e. you can't have 2,2).
Also, order is not important. So 1,2 is the same as 2,1.

9 ways of selecting 1item
36 ways of selecting 2 items
84  ways of selecting  3 items
126 ways of selecting 4 items
126 ways of selecting 5 items
84 ways of selecting 6 items
36 ways of selecting 7 items
9 ways of selecting 8. items
1 ways of selecting 9 items
Total ways are 511
