So, Chris and I were talking at lunch the other day, and we wound up talking ourselves into a mathematical corner, from which two strategy/user experience/geek/etc brains could not emerge intact.
So if anyone can help us figure out this (undoubtedly simple, but not to us) thing, speak up:
Say you had three arrays, each with 20 things in. Knowing that a “set” had to contain one item each from arrays A, B and C, how many possible unique sets are there?
Perhaps I am missing something, but would it not be:
(possible choices from first array) x (possible choices from second array) x (possible choices from third array)
And thus,
20 x 20 x 20 = 8000
?
Yeah, exponentiation. 20 to the power 3 = 8000 possible combinations.
Aha!
I think this was a case of us thinking too much about the problem - we came up with 8000 and then thought “no, it must be harder than that…”
Blame jet-lag and a liberal education.
Thanks!
Phew. I was going to suggest that, but my maths skills are ropey at times and I wasn’t confident enough. Lurker’s summary is perfect: all possible choices multiplied together.
Well, I got 8000 as well, which is a relief. I thought for an awful moment your question was for sets of any size from 3 to 60, which is rather tougher. (And God, no, I’ve no idea.)