document.write( "Question 298192: Maurice wants to multiply together two numbers composed of two digits each. Unfortunately, he reverses the digits of one of the numbers and obtains a result which is greater than the exact result by 3015. Which of the following could be one of the numbers?\r
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document.write( "(A) 23 (B) 38 (C) 45 (D) 62 (E) 81 \n" );
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Algebra.Com's Answer #214572 by amoati(11) ![]() You can put this solution on YOUR website! Let's assume that the numbers are A & B and it was B that Maurice reverses.\r \n" ); document.write( "\n" ); document.write( "Since B is 2 digits number we can say that B = W + 10 Y\r \n" ); document.write( "\n" ); document.write( "So the exact result would be A * (W + 10 Y) and when he reserves the digits of the B number, the result would be A * (Y + 10 W)\r \n" ); document.write( "\n" ); document.write( "So the difference would be A * (Y + 10 W) - A * (W + 10 Y) = 3015\r \n" ); document.write( "\n" ); document.write( "So A * (Y + 10 W - W -10 Y) = 3015\r \n" ); document.write( "\n" ); document.write( "A * (9 W - 9 Y) = 3015\r \n" ); document.write( "\n" ); document.write( "dividing by 9\r \n" ); document.write( "\n" ); document.write( "A * (W - Y) = 335\r \n" ); document.write( "\n" ); document.write( "335 is the multiplication of 5 * 67 (67 is a prime number)\r \n" ); document.write( "\n" ); document.write( "So the difference between the two digits of the B number is 5\r \n" ); document.write( "\n" ); document.write( "then the correct answer would be (B) 38\r \n" ); document.write( "\n" ); document.write( "In fact we can verify our answer since now we know both numbers A = 67, B = 38\r \n" ); document.write( "\n" ); document.write( "So A * B = 67 * 38 = 2546 and when B is reserved 67 * 83 = 5561 and the difference 5561 - 2546 = 3015 :) \n" ); document.write( " |