Fractions in Lowest Terms
A fraction is said to written using lowest terms if its numerator and denominator are relatively prime , that is, they have no common factors other than . (Some books use "simplest form" to mean the same thing.)
So, is written in lowest terms, since and have no common factors other than . But is not; and have a common factor .
To write in lowest terms, divide both the numerator and denominator by the greatest common factor , in this case :
So written in lowest terms is .
This is known as reducing fractions .