document.write( "Question 1141460: My child has been given this question in homework.\r
\n" );
document.write( "\n" );
document.write( "I am thinking of a 3 digit number
\n" );
document.write( "When it is divided by 9, the remainder is 3
\n" );
document.write( "When it is divided by 2, the remainder is 1
\n" );
document.write( "When it is divided by 5, the remainder is 4
\n" );
document.write( "What is my number? \n" );
document.write( "
Algebra.Com's Answer #761994 by greenestamps(13203)![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "(1) divided by 5 leaves remainder 4 --> last digit is either 4 or 9 \n" ); document.write( "(2) divided by 2 leaves remainder 1 --> last digit is odd \n" ); document.write( "From (1) and (2), the last digit is 9. \n" ); document.write( "That much is fairly basic and can be understood by fairly young children. The last part is more advanced. \n" ); document.write( "A number is divisible by 9 if, and only if, the sum of the digits is a multiple of 9. As a corollary to that, a number will leave a remainder of 3 when divided by 9 if, and only if, the sum of the digits is 3 more than a multiple of 9. \n" ); document.write( "So with last digit 9, the sum of the other two digits has to be 3 more than a multiple of 9 -- i.e., either 3 or 12. Fortunately there are many 3-digit numbers that satisfy these conditions. \n" ); document.write( "Sum of other two digits = 3: 129, 219, 309. \n" ); document.write( "Sum of other two digits = 12: 399, 489, ... 939. \n" ); document.write( "The way the problem is presented, it sounds as if there is supposed to be a single answer. Clearly there are multiple possible answers if the number is 3 digits. \n" ); document.write( "There would only be a single answer if the number were 2 digits. Is it possible that that is what the problem is supposed to be? \n" ); document.write( " |