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What is the value of the arithmetic series $28 + 30 + 32 + .... + 86$?

 Sep 12, 2017
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28 + 30 + 32 + .... + 86

 

Note....that we can pair the terms as follows

 

[ 28 + 86 ] + [ 30 + 84] + [ 32 + 82 ] +......+ [56 + 58]

 

Each pair sums to 114

 

And the number of pairs is given by   [56 - 28] / 2 + 1  = 15 pairs

 

So...the sum is   15 * [ 114 ]  =    1710

 

 

cool cool cool

 Sep 12, 2017
edited by CPhill  Sep 12, 2017

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