+0  
 
0
79
4
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Compute 1 - 2 + 3 - 4 +... + 2005 - 2006 + 2007 - 2008 + 2009 - 2010.

 Apr 13, 2022
 #1
avatar+61 
+2

(1 - 2) + (3 - 4) + (5 - 6) + ... + (2003 - 2004) + (2005 - 2006) + 2007

= -1+(-1)+(-1) (1005 times)

=  -1005

 Apr 13, 2022
edited by qjin27  Apr 13, 2022
edited by qjin27  Apr 13, 2022
 #2
avatar+578 
+1

You eventually get:

 

-1 + -1 + -1 + 2007(for 1005 terms)

 

So 

 

-1005 

 

 

smileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmileysmiley

 Apr 13, 2022
edited by Vinculum  Apr 13, 2022
 #3
avatar+61 
+1

uh I think it goes to -2010, not 2007

qjin27  Apr 13, 2022
 #4
avatar+578 
+2

Whoops, thx for catching that @qjin27

 Apr 13, 2022

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