document.write( "Question 1076650: Find the sum of the multiples of 3 less than 100. Hence or otherwise find the sum of the numbers less than 100 which are not multiples of 3. \n" ); document.write( "

Algebra.Com's Answer #691296 by math_helper(2461) $\"\"$ $\"About$

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3*1 = 3
\n" ); document.write( "3*2 = 6
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\n" ); document.write( "3*33 = 99\r
\n" ); document.write( "\n" ); document.write( "So there are 33 multiples of 3 less than 100. To find the sum, use $\"+sum%28i%2C+i=1%2Ci=n%29+=+%28n%2A%28n%2B1%29%29%2F2+\"$ and then multiply the result by 3:\r
\n" ); document.write( "\n" ); document.write( " 3+6+9 +… + 99 = 3(1+2+3+…+33) = $\"+3%2Asum%28i%2C+i=1%2C+i=33%29+=+3%2A%2833%2A34%2F2%29+=+highlight%281683%29+\"$
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\n" ); document.write( "To find the sum of numbers less than 100 that are not multiples of 3, I would take the approach of finding the sum of all the numbers less than 100 $\"+sum%28i%2C+i=1%2C+i=99%29+=+99%2A100%2F2+\"$ and then subtract from that result, the sum of the multiples of 3 we found above.\r
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