1) A fraction represents a part of a whole. The numerator represents the parts and the denominator represents the whole. 2) To convert a fraction to a decimal, you divide the numerator by the denominator. To convert a decimal to a fraction, you write the place value as the denominator and the number as the numerator. 3) When adding or subtracting fractions, you need common denominators. You find the least common multiple and use it to convert the fractions before adding or subtracting the numerators.