In pre-algebra section, there are basic rules for arithmetic operation.
For example, what is the common factors? What is the greatest common factor (GCF)? What is the simplest form of a fraction? What is the least common denominator (LCD)? How to comparing fractions with common denominators? How to comparing fractions with different denominators? How to compare fractions with the same numerators and different denominators? How to change a mixed number to a fraction? How to add
two fractions with the same denominator? How to add two fractions with different denominators? How to add two mixed numbers with the same denominator? How to add two
mixed numbers with different denominators? How to subtract two fractions with the same denominator? How to subtract two fractions with different denominators? How to
subtract two mixed numbers with the same denominator? How to subtract two mixed numbers with different denominators? How to multiply two fractions? How to divide two
fractions? Why do we need to use a fraction? Look the example, on hour is 60 minutes, then 20 minutes is how many hours? The 20 minutes is 20/60 = 1/3 hours which
is a fraction. So, a part of whole can be expressed as a fraction. There are a lot of operation rules in Pre-algebra, it is the foundation of the algebra.