document.write( "Question 604611: how you get the sum of all the whole natural numbers greater than 89 and less than 101 \n" ); document.write( "
Algebra.Com's Answer #381304 by Edwin McCravy(20060)\"\" \"About 
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how you get the sum of all the whole natural numbers greater than 89 and less than 101.
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document.write( "One way is just to add up the 11 numbers:\r\n" );
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document.write( "90+91+92+93+94+95+96+97+98+99+100 = 1045\r\n" );
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document.write( "The other way is to use the sum formula for an arithmetic sequence:\r\n" );
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document.write( "Sn = \"n%2F2\"(a1 + an) \r\n" );
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document.write( "where n = 11, \r\n" );
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document.write( "S11 = \"11%2F2\"(a1 + a11)\r\n" );
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document.write( "then use\r\n" );
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document.write( "a1 = 90, and a11 = 100\r\n" );
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document.write( "S11 = \"11%2F2\"(90 + 100)\r\n" );
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document.write( "S11 = \"11%2F2\"(190)\r\n" );
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document.write( "S11 = \"11%2F2\"(190) = 1045.\r\n" );
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document.write( "Edwin
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