document.write( "Question 1034674: what is the sum of the first 100 natural Numbers excluding the multiples if 4 \n" ); document.write( "
Algebra.Com's Answer #649336 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
That's (1+2+3+...+99+100)) - (4+8+12+...96+100)\r\n" );
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document.write( "There are 100 natural numbers \r\n" );
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document.write( "there are 25 multiples of 4 through 100, because if \r\n" );
document.write( "you divide all the numbers 4,8,12,...,96,100 by 4, \r\n" );
document.write( "you get 1,2,3,...,24,25. \r\n" );
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document.write( "We use the formula for the sum of an arithmetic series\r\n" );
document.write( "with n terms, first term a1, nth term an. \r\n" );
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document.write( "\"S%5Bn%5D\"\"%22%22=%22%22\"\"expr%28n%2F2%29%28a%5B1%5D%2Ba%5Bn%5D%29\"\r\n" );
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document.write( "(1+2+3+...+99+100)) - (4+8+12+...96+100) = \r\n" );
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document.write( "\"expr%28100%2F2%29%281%2B100%29\"\"%22%22-%22%22\"\"expr%2825%2F2%29%284%2B100%29\"\r\n" );
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document.write( "\"expr%2850%29%28101%29\"\"%22%22-%22%22\"\"expr%2825%2F2%29%28104%29\"\r\n" );
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document.write( "\"expr%2850%29%28101%29\"\"%22%22-%22%22\"\"expr%2825%2A52%29\"\r\n" );
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document.write( "\"5050+-+1300\"\r\n" );
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document.write( "\"3750\"\r\n" );
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document.write( "Edwin
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