Decaflon Thread: Looking For Math Formula: Pairs

Looking For Math Formula: Pairs

Scrivs — Wed, 19 Mar 2008 08:22:00

Yeah I figured it was some type of combination, but had no idea the binomial coefficient stuff. That formula brings back nightmares of Probability class in college.

Looking For Math Formula: Pairs

touqen — Wed, 19 Mar 2008 00:44:56

I think you're looking for Combinations (or Binomial Coefficients).
http://mathworld.wolfram.com/Combination.html

I <3 mathworld.

Looking For Math Formula: Pairs

Ozone42 — Wed, 19 Mar 2008 00:16:46

There's probably a name for this. It's like a factorial subset.

Looking For Math Formula: Pairs

RightOn — Tue, 18 Mar 2008 22:29:36

You're talking to a guy who took College Algebra 3 times, and who probably uses the Calculator.app on his iPod Touch more than anyone else on the planet because he can't do basic 4 function math in his head.

Looking For Math Formula: Pairs

Scrivs — Tue, 18 Mar 2008 22:15:11

Ah come on it wasn't that bad, took me about 10 minutes and that is after realizing I originally messed up on the 8-10 sequence.

Looking For Math Formula: Pairs

RightOn — Tue, 18 Mar 2008 22:11:06

WOW!

This is your post > ---

This is my head > O

Looking For Math Formula: Pairs

joshawesome — Tue, 18 Mar 2008 21:38:15

I was helping my sister with her math homework last night. It took me four hours just to check her work and make sure she did it right. I haven't done any sort of trig in ten years, so it was a bit rough at first, but i figured it all out in the end.

Looking For Math Formula: Pairs

Scrivs — Tue, 18 Mar 2008 13:46:25

I'm in one of my mythical work spurts.

Looking For Math Formula: Pairs

shadowsun7 — Tue, 18 Mar 2008 13:29:56

I was actually thinking of a probability formula like 12P2, but then you up and solved it. You should be sleeping, Scrivs. ;P

Looking For Math Formula: Pairs

Scrivs — Tue, 18 Mar 2008 12:37:32

Well I couldn't sleep till I got it and it really wasn't that hard (maybe the reason why I couldn't sleep. If n equals the total number in the set then formula is (n-1)*n/2. Pretty damn simple.

Looking For Math Formula: Pairs

Scrivs — Tue, 18 Mar 2008 12:28:28

I'm going under the excuse that it is 4:22am and my brain can't figure this out. What I am looking for is a formula that will tell me how many pairs I can make from a set of numbers.

For example if I have the numbers 1,2,3,4 then the possible pairs are:

I can see the pattern in my head, but can't devise a formula for some reason.

Set of 2 = 1 pair
Set of 3 = 3 pairs
Set of 4 = 6 pairs
Set of 5 = 10 pairs
Set of 6 = 15 pairs
Set of 7 = 21 pairs
Set of 8 = 28 pairs
Set of 9 = 36 pairs
Set of 10 = 45 pairs

I know some genius here can pop out the formula for me.