1. ## Permutation Help

I'm struggling to get my head around the amount of combinations I can have from 6 letters, ranging from a single letter upto 6 letters. They mustn't be the same combination twice such as abcdef is the same as acdfeb.

the letters are a, b, c, d, e, f

i know the obvious ones like

a
b
c
d
e
f
ab
ac
ae
af
bc
bd
be
bf

and so on, can someone help with all the possible combinations or know a quick way to work them all out, thanks in advance if you can help

2. ## Re: Permutation Help

Originally Posted by Trifolium
I'm struggling to get my head around the amount of combinations I can have from 6 letters, ranging from a single letter upto 6 letters. They mustn't be the same combination twice such as abcdef is the same as acdfeb.
the letters are a, b, c, d, e, f
You are simply asking for the number of non-empty subsets of set six: $2^6-1$

3. ## Re: Permutation Help

The letter a can be either in the subset or not. For each of the two possibilities, the letter b can be either in or out, and so on. Note that you exclude the empty subset.