document.write( "Question 1191246: What is the sum of 1 - 2 + 3 - 4 + 5 - ... + 399 - 400? \n" ); document.write( "

Algebra.Com's Answer #823049 by ikleyn(52794) $\"\"$ $\"About$

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document.write( "Group/re-group this sum in pairs.\r\n" );
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document.write( "You will have 400/2 = 200 pairs, each pair has the sum of -1.\r\n" );
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document.write( "Therefore, the total sum is -200.    ANSWER\r\n" );
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