document.write( "Question 871518: find the number of integers smaller than and are relatively prime to 80 \n" ); document.write( "
Algebra.Com's Answer #525573 by Edwin McCravy(20065)\"\" \"About 
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document.write( "find the number of integers smaller than and are relatively prime to 80\r\n" );
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document.write( "            80\r\n" );
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document.write( "         10    8\r\n" );
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document.write( "        2  5  2  4 \r\n" );
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document.write( "                2  2\r\n" );
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document.write( "The only prime factors of 80 are 2 and 5. So those\r\n" );
document.write( "relatively prime to 80 cannot be divisible by 5.\r\n" );
document.write( "So they cannot end in an even digit or 5.  So they\r\n" );
document.write( "must end in either 1,3,7, or 9\r\n" );
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document.write( "We will think of 1-digit numbers as 2-digit numbers\r\n" );
document.write( "with first digit 0, like 1 = 01, 2 = 02, etc.\r\n" );
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document.write( "To be less than 80 the first digit can only be 0,1,...,7\r\n" );
document.write( "So there are 8 choices for the first digit.\r\n" );
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document.write( "For each of those 8 choices for the first digit,\r\n" );
document.write( "there are 4 choices for the last digit 1,3,7,9,\r\n" );
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document.write( "Answer 4×8 = 32\r\n" );
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document.write( "Here they all are:\r\n" );
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document.write( " 1,  3,  7,  9, 11, 13, 17, 19,\r\n" );
document.write( "21, 23, 27, 29, 31, 33, 37, 39, \r\n" );
document.write( "41, 43, 47, 49, 51, 53, 57, 59, \r\n" );
document.write( "61, 63, 67, 69, 71, 73, 77, 79.\r\n" );
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document.write( "Edwin
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