+0  
 
+1
238
2
avatar+973 

Compute \(1 - 2 + 3 - 4 + \dots + 2005 - 2006 + 2007\).

 Sep 1, 2018
 #1
avatar+3994 
+2

Hint: Try to combine the terms!

 Sep 1, 2018
 #2
avatar+374 
+2

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

 Sep 1, 2018

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