quick way to count

by steven gerrard   Last Updated October 20, 2019 05:20 AM - source

Suppose we have 10 sticks with length 1-10, respectively. Pick three from them, how many triangles can we form?

I counted one by one and got 50. Is there a quick way? Any help would be appreciated.

Tags : combinatorics


Related Questions



Combinatorics problem on the size of A+B

Updated April 22, 2015 22:08 PM

Certain property of finite field $F_p$

Updated September 27, 2017 02:20 AM

Constant sum of characters

Updated August 16, 2018 13:20 PM