When children begin division they usually write the question with a remainder. However, remainders can be written as fractions, making a more accurate and complete division answer.
For example a remainder of one when dividing by two can be written as one over two or one half. This is no longer a remainder but a part of the answer. So 17 divided by 2 is 8 remainder 1 or 8 and 1/2.
Used in the real world this would mean that if there were 17 bars of chocolate to divide between two children they would get eight and a half each, rather than eight and one left over (remainder).
When doing this the remainder goes on the top line of the fraction (numerator) and the bottom number (denominator) is the number which has been divided by.