document.write( "Question 217487: What is the sum of the positive multiples of 13 that are less than 300? \n" ); document.write( "

Algebra.Com's Answer #164082 by MathTherapy(10555) $\"\"$ $\"About$

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The sum of a series of numbers = the average of the numbers, times the number of numbers\r
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\n" ); document.write( "\n" ); document.write( "Since we’re looking for all multiples of 13 that are less than 300, we start at 13 (13 * 1) and end at 299 (300 / 13, and then round down). This means that the multiples begin at 13 and end at 299.\r
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\n" ); document.write( "\n" ); document.write( "Now, since the least multiple is multiplied by 1, and the largest is multiplied by 23, then we’re going to have a total of 23 multiples (23 – 1 + 1).\r
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\n" ); document.write( "\n" ); document.write( "The average of the series of numbers that we’re looking for is 156 ( $\"%2813+%2B+299%29%2F2\"$ ), and since the number of numbers in the series is 23, the sum of the positive multiples of 13 that are less than 300 = 156 * 23 = $\"highlight_green%283588%29\"$
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