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Talk:2013 AMC 12A Problems/Problem 20

Revision as of 18:16, 25 November 2019 by Vsamc (talk | contribs) (Created page with "Disucssion: COuld someone please explain how you got the first set of conditions is <math>45*10-\sum_{k=1}^{9}\dbinom{k+1}{2}</math>? Thank you!")
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Disucssion:

COuld someone please explain how you got the first set of conditions is $45*10-\sum_{k=1}^{9}\dbinom{k+1}{2}$? Thank you!

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