document.write( "Question 234983: 1-2 + 3 -4 + ....-98 + 99 equals \r
\n" ); document.write( "\n" ); document.write( "a) -50 b) -49 c) 0 d) 49 e) 50
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Algebra.Com's Answer #173188 by Alan3354(69443)\"\" \"About 
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1-2 + 3 -4 + ....-98 + 99 equals
\n" ); document.write( "a) -50 b) -49 c) 0 d) 49 e) 50
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\n" ); document.write( "There are 99 numbers.
\n" ); document.write( "Put them in pairs,
\n" ); document.write( "1+99 = 100
\n" ); document.write( "-2-98 = -100
\n" ); document.write( "...
\n" ); document.write( "49+51 = 100 It's all even, at zero, to this point
\n" ); document.write( "Then the -50 has nothing to pair with
\n" ); document.write( "--> = -50
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