The Algebra Teacher\'s Guide to Reteaching Essential Concepts and Skills

Teaching Notes 2.15: Expressing Fractions as Percents

Fractions can be expressed as percents via two different methods: changing the fraction to a

decimal and then expressing the percent or writing an equivalent fraction and then expressing

the fraction as a percent. Most mistakes result fromnot understanding the steps to the methods.

1. Explain that a percent is a number that represents a rate per hundred. Percents, therefore,
   are always based on a hundred. For example, if 60 out of 100 eighth-graders prefer pizza for
   lunch, 60 percent prefer pizza.


2. Review the two methods for changing fractions to percents and the examples on the work-
   sheet with your students.
   
   
   • Point out that in method 1, there must be a digit in both the tenths and hundredths
     place. Depending on the abilities of your students, you may find it helpful to show the
     steps of long division.
   
   
   • Suggest that students may prefer to use method 2 when the denominator of the fraction
     is a factor of 100 because it is then easier to write the equivalent fraction. Depending on
     your students’ abilities, you may find it helpful to review solving proportions.
   
   
   • Note the examples of changing^3
     8
   
   
   
   

to a percent. In method 1, the remainder is written as a

fraction. In method 2, the remainder is written in decimal form. Both are correct.

EXTRA HELP:

Mixed numbers can be changed to percents that are greater than 100 percent by changing the

mixed number to an improper fraction and using method 1 or method 2.

ANSWER KEY:

(1)60% (2) 87

1

2

% or 87.5% (3) 66

2

3

%or66.6% (4)

7

10

%or0.7% (5)9% (6) 16

2

3

%or16.6%

(7)67% (8)350% (9) 90 .90% (10) 77 .7% (11)262.5% (12) 8 .3%

------------------------------------------------------------------------------------------

(Challenge)Disagree. It should read that whole numbers greater than 1 and all mixed numbers

can be expressed as percents greater than 1. 1 is equal to 100 percent.

------------------------------------------------------------------------------------------

76 THE ALGEBRA TEACHER’S GUIDE