SAT Subject Tests in Math

Variables in the Denominator Fraction problems get more difficult to solve when there is a variable in the denominator. To solve, find the least common denominator (LCD) of the fractions, and multiply both sides of the equation by it. E X A M P L E : Solve The LCD …

Using Mixed Numbers and Improper Fractions A mixed number represents the sum of an integer and a fraction. In fractional form: When is written as the fraction it is called an improper fraction. Improper fractions are fractions whose numerator is greater than the denominator. It is often easier to change …

Multiplying Fractions To multiply fractions, simply multiply straight across. E X A M P L E : Simplify Divide by a common factor to simplify. (Answer) You can also simplify the fractions before multiplying to save time.

Least Common Denominator The least common denominator (LCD) of two or more fractions is the least common multiple (LCM) of their denominators. To find the LCD: 1. Factor each denominator completely and write as the product of prime factors. (Factor trees are usually used for this.) 2. Take the greatest …

Simplifying Fractions Fractions are in simplest form when the numerator and denominator have no common factor other than 1. To simplify a fraction, factor both the numerator and denominator. Don't cancel terms that are not common factors. Below is a common mistake: