SOLUTION: The value of 9C2

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Question 924801: The value of 9C2
Found 2 solutions by ewatrrr, MathLover1:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
9C2 = 9!/(2!7!) = 9%2A8%2F%282%2A1%29 = 36
...
Casio fx-115 ES plus is a relatively inexpensive calculator ...
that does Combinations and Permutations and a 'whole lot more'
...
Recommend Using Calculators to Check one's work.

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

+C%28n%2Cr%29=n%21%2F%28%28n-r%29%212%21%29+

+C%289%2C2%29=9%21%2F%28%289-2%29%212%21%29+

+C%289%2C2%29=%289%2A8%2A7%2A6%2A5%2A4%2A3%2A2%2A1%29%2F%28%287%29%212%21+%29





+C%289%2C2%29=9%2A4

+C%289%2C2%29=36

So 9 choose 2 (where order does not matter) yields 36 unique combinations.