In fractional math, a numerator is the top number in a fraction, and the denominator is the bottom number. In the fraction one-half, for instance, one is the numerator, and two is the denominator.
Another difference is that the denominator indicates the total parts of a whole, and the numerator is the amount of the whole being assessed. In one-half, the whole is two parts and one is the portion of the parts. To convert a fraction to a decimal point, one divides the numerator by the denominator. The slash between the numbers is akin to a division sign. Thus, one divided by two equals 0.5.