SOLUTION: 1 + 2 + ... + 80

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Question 988472: 1 + 2 + ... + 80
Answer by Alan3354(69443) About Me  (Show Source):
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1 + 2 + ... + 80
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There are 80 elements.
The average is (1+80)/2 = 40.5
--> 80*40.5
= 3240