Hi,
Im sure there is an easy answer to my question, but its been a while since maths class and I cant seem to work it out in my head!
Imagine I have two objects, lets call them 'A' and 'B', what I want to do is work out a formula for the total number of possible combinations of the objects, with repeats not allowed. so... for two letters the possibilities are:
1)A
2)B
3)A+B
3 possible combinations (B+A isnt valid as its the same as A+B as far as im concerned).
and for three letters:
1)A
2)B
3)C
4)A+B
5)A+C
6)B+C
7)A+B+C
(7 combinations)
what I would ideally like would be a formula for N objects! I understad the use of factorials (n!) in similar problems, but cant quite find the way to relate it to this... Can anyone help me?
Thanks!
Imagine you were also allowed to select none of the objects.
For 1 object, you have 2 choices
{} {A}
For 2 objects, double the number of choices
{} {A} {B} {AB}
For 3 objects, double the number of choices
{} {A} {B} {AB} {C} {AC} {BC} {ABC}
Keep doubling, so the number of choices is a power of 2.
Then reduce it by 1 choice.