SOLUTION: Find the value of 1-2+3-4+4-6+...-100

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Question 1201805: Find the value of 1-2+3-4+4-6+...-100
Found 3 solutions by josgarithmetic, ikleyn, greenestamps:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
That either broke the sequence or it contains a mistake.

Answer by ikleyn(52778) About Me  (Show Source):
You can put this solution on YOUR website!
.
Find the value of 1-2+3-4+4-6+...-100
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There are SEVERAL errors in your post (several here means "more than one").

Fix them; then re-post to the forum.

Please do not post it to me in person.



Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Find the value of 1-2+3-4+cross%284%295-6+...-100

Presumably that is the expression you need to evaluate. It doesn't take a lot of effort to look at what you are posting before you post it, to see it you are posting it correctly....

1-2+3-4+5-6+...+99-100

Group the terms in pairs:

(1-2)+(3-4)+(5-6)+...+(99-100)

(-1)+(-1)+(-1)+...+(-1)

That's 50 pairs, each with a sum of -1, so the sum of all the numbers is 50(-1) = -50.

ANSWER: -50