Unit 6 Addition of Common Fractions Basic Principles

Unit 6 Addition of Common Fractions

Basic Principles of Addition of Common Fractions • A common or proper fraction is a quantity that is smaller than a whole number. It represents a part of a whole. • An example is 2/3. – This fraction means that a whole number has been divided into three parts, and the quantity equals two of the three parts.

Basic Principles of Addition of Common Fractions • The number above the line in a common fraction is called the numerator. • The number below the line is called the denominator: Numerator → Denominator →

Basic Principles of Addition of Common Fractions • When common fractions are added, the denominator of each fraction must be the same. – When the denominators are all the same, only the numerators are added. The sum obtained is then placed over the common denominator. – If the denominators are not the same, a lowest common denominator must be found. This is the smallest number that all of the denominators can be divided into evenly.

Addition of Common Fractions • Example: Find the sum: – First find the lowest common denominator: – Add and reduce the answer to its lowest terms:

Addition of Mixed Numbers • An improper fraction is a fraction in which the numerator is greater than the denominator. • A mixed number is a mixture of a whole number and a fraction.

Addition of Mixed Numbers • To add mixed numbers, line up the numbers in a column. – Add the whole numbers first. – Make sure the fractions have a common denominator. – Add the fractions and write the sum obtained over the common denominator. – Reduce the fraction as necessary.

Addition of Mixed Numbers • Example: Find the sum: – Line up the numbers: – Find a common denominator and add: – Reduce to lowest terms:

Practical Problem • A surgical nurse in an outpatient surgical clinic works 1 1/4 hours in preoperative care (before surgery), 2 1/2 hours in the operating room, and 3 3/4 hours in the recovery room. • How many hours does she work each day?

Practical Problem • Line up the fractions and add: • The nurse works hours each day.