Compute 1−2+3−4+⋯+2005−2006+2007.
Hint: Try to combine the terms!
We can see that 1−2=−1, 3−4=−1, ... all the way to 2005−2006=−1. 2007 has no pair, so we will save that number for later. There are 1003 pairs of numbers, which means there are one thousand and three −1's. So we have −1003+2007=1004.
- Daisy
