SOLUTION: What is the sum of 1 - 2 + 3 - 4 + 5 - ... + 399 - 400?

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Question 1191246: What is the sum of 1 - 2 + 3 - 4 + 5 - ... + 399 - 400?
Answer by ikleyn(52790) About Me  (Show Source):
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Group/re-group this sum in pairs.


You will have 400/2 = 200 pairs, each pair has the sum of -1.


Therefore, the total sum is -200.    ANSWER

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