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2006 Alabama ARML TST Problems/Problem 2

Revision as of 13:21, 2 March 2008 by 1=2 (talk | contribs) (New page: ==Problem== Compute <math>\sum_{k=1}^{5}\sum_{n=1}^{6}kn</math>. ==Solution== For each value of k, the sum is equal to <math>1k+2k+3k+4k+5k+6k=21k</math>. <math>\sum_{k=1}^{5}21k=21*15=\...)
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Problem

Compute $\sum_{k=1}^{5}\sum_{n=1}^{6}kn$.

Solution

For each value of k, the sum is equal to $1k+2k+3k+4k+5k+6k=21k$.

$\sum_{k=1}^{5}21k=21*15=\boxed{315}$

See also

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