SOLUTION: What is the value of 12C2?

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Question 1186044: What is the value of 12C2?
Found 3 solutions by MathLover1, MathTherapy, ikleyn:
Answer by MathLover1(20849) About Me  (Show Source):
Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

What is the value of 12C2?
NEVER, EVER follow that woman's suggestion regarding answering most math problems!

This is NOT done the way she shows!



This problem DOESN"T require a calculator as some people - including the other person - would suggest!

Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.

For nC2, there is a simple and compact formula  


    nC2 = C%5Bn%5D%5E2 = %28n%2A%28n-1%29%29%2F2.


In your case,  12C2 = %2812%2A%2812-1%29%29%2F2 = %2812%2A11%29%2F2 = 6*11 = 66.



It is highly recommended for any student to know and to use this simple formula,

alongside with the long formulas for the general case.



Using the short compact formula will allow you to save huge amount of your time and avoid numerous errors,

which you DEFINITELY and INEVITABLY will make, using long formulas without any visible benefits.


Solved.