2 – 4 + 6 – 8 + 10 – 12 + . . . 994 – 996 + 998 – 1000 = A) -250 B) -498 C) -500 D) -998 E) -1000 Oops, I fogot to make all of the answers negative (the original question featured only 1 negative answer) The corrected answer choices are now displayed - sorry

Should it not be -500.?? I am missing something. Between 2 to 1000 there are 500 evens and 499 odd's 2-4+6-8 = -4 Sum of each set of 4 is -4 500/4 = 125 sets possible 125*-4 = -500

Just saw ur corrected post. Thanks! Regards, Cramya

Just trying my way to beat this one. 2,-4,6,-8,10,-12......., 1)If you add two terms you will get 2 ( 2-4 or 6-8 or 10-12) etc. 2) Find how many two's you will get like this: i.e...(1000-2)/2 +1 = 500. 3) 500 * 2 = 1000. Let me know does it make sense.

Just trying my way to beat this one. 2,-4,6,-8,10,-12......., 1)If you add two terms you will get -2 ( 2-4 or 6-8 or 10-12) etc. 2) Find how many two's you will get like this: i.e...(1000-2)/2 +1 = 500. 3) 500 * -2 = -1000. Let me know does it make sense.

canindia wrote:Just trying my way to beat this one. 2,-4,6,-8,10,-12......., 1)If you add two terms you will get -2 ( 2-4 or 6-8 or 10-12) etc. 2) Find how many two's you will get like this: i.e...(1000-2)/2 +1 = 500. 3) 500 * -2 = -1000. Let me know does it make sense. This looks good. The only problem is that there aren't 1000 terms in 2 – 4 + 6 – 8 + 10 – 12 + . . . 994 – 996 + 998 – 1000. We are skipping all of the odd numbers, so there are 500 terms (or 250 pairs that add to -2) Here's my solution as well: 2 – 4 + 6 – 8 + 10 – 12 + . . . 994 – 996 + 998 – 1000 = (2 – 4) + (6 – 8) + (10 – 12) + . . . +(994 – 996) + (998 – 1000) = (-2) + (-2) + (-2) + . . . (-2) + (-2) How many -2’s must we add? The original sum, 2 – 4 + 6 – 8 + 10 – 12 + . . . 994 – 996 + 998 – 1000 consists of 500 pieces “addends,” which means that there were 250 pairs of numbers (which added to -2) Sum = 250(-2) = -500

I agree with Cramya on this one. Here's what I did: Each -2 comes after adding 4 to each term. For example: 2+4=6, 6+4=10 This is a perfect example of an arithmetic sequence. an=dn+c an=4n-2 998=4n-2 n=250 -2(250)=-500 C