SOLUTION: What is the value of 1 − 2 + 3 − 4 + ... + 99 − 100 (alternating signs for each term)?

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Question 258317: What is the value of 1 − 2 + 3 − 4 + ... + 99 − 100 (alternating signs for each term)?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
1-2=-1
3-4=-1
5-6=-1
7-8=-1
9-10=-1
.
.
.
99-100=-1
You have 50 pairs of differences each of which equals (-1).
Sum=50%28-1%29=-50.