document.write( "Question 1191252: Let D = 0.5727272... be an infinite repeating decimal with the digits 7 and 2 repeating. When D is written as a fraction in lowest terms, by how much does the denominator exceed the numerator? \n" ); document.write( "
Algebra.Com's Answer #823061 by math_tutor2020(3817)![]() ![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "First multiply both sides by 10 to move the decimal over one spot to the right. \n" ); document.write( "D = 0.5727272... \n" ); document.write( "10D = 5.727272... \n" ); document.write( "Take note of the decimal digit sequence 727272... \n" ); document.write( "In other words, we have 72 repeating forever. \n" ); document.write( "The order is important.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now go back to the original equation. \n" ); document.write( "Multiply both sides by 1000 to move the decimal over 3 spots to the right. \n" ); document.write( "D = 0.5727272... \n" ); document.write( "1000D = 572.727272... \n" ); document.write( "Once again, we have the exact sequence of 72 repeated forever. \r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So, \n" ); document.write( "10D = 5.727272... \n" ); document.write( "1000D = 572.727272...\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Once again, the order of the decimal digits is important. This way we can subtract them and have them cancel.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "1000D - 10D = (572.727272...) - (5.727272...) \n" ); document.write( "990D = (572 + 0.727272...) - (5 + 0.727272...) \n" ); document.write( "990D = 572 + 0.727272... - 5 - 0.727272... \n" ); document.write( "990D = (572 - 5) + \n" ); document.write( "990D = 567 \n" ); document.write( "The decimal portions are completely gone at this point.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Then we divide both sides by 990 and reduce. \n" ); document.write( "990D = 567 \n" ); document.write( "990D/990 = 567/990 \n" ); document.write( "D = 567/990 \n" ); document.write( "D = (63*9)/(110*9) \n" ); document.write( "D = 63/110\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "As a check, use your calculator to see that \n" ); document.write( "63/110 = 0.572727272727 \n" ); document.write( "which is approximate. \n" ); document.write( "Unfortunately and realistically, the calculator cannot display infinitely many digits.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Or your calculator may display this \n" ); document.write( "63/110 = 0.57272727273 \n" ); document.write( "The 3 at the end is the result of rounding error. It should be a 2. The rounding occurs because the next digit over (7) is larger than 5. \n" ); document.write( "Despite this rounding error, if it arises, it's not enough to derail things. We have enough proof that 63/110 is the fraction form of the decimal 0.5727272...\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "By the point of arriving at the fraction 63/110, we simply subtract the numerator and denominator to find the difference between them.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "110-63 = 47\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The denominator exceeds the numerator by 47 in the reduced fraction. \n" ); document.write( " \n" ); document.write( " |