Step by Step Lesson on Percentage

Percent

Percent: Basics

Percent

• Definition: per 100

• Look at the diagrams on slide one. Each of those show 100 squares. Shading in a number of those squares will give you a fraction of squares shaded out of 100.

• The first example shows 84 squares shaded. That is the fraction

   $\frac{84}{100}$  we learned in Chapter 3 that the decimal would be .84.  Since per cent means per 100, we can say there is 84%.

Decimal Review

• When you have a decimal value of .8 we can write this as a fraction of

   $\frac{80}{100}$  keeping the denominator as 100 because we are working with percent.

• Now that the fraction is written we can say we have 80%.

Percent to decimals

• 50% can be changed to the fraction

   $\frac{50}{100}$  and simplified to  $\frac{1}{2}$  .

• The decimal value will be .5?  Can you determine why this is the answer?

• Take the calculator and divide 50 by 100.  What is the answer?

Decimals to percent

•  $\frac{50}{100}$  

  Again, if we take the fraction above and write it as a decimal, we would have .5.

• To make this into a percent, multiply the decimal by 100.  This will be 50%.

Mixed numbers and percent

• A mixed number such as 3 $\frac{4}{10}$  can be written as a decimal of 3.4.

• By multiplying the decimal by 100, you can change this into a percent.  This would be 340%.  

• Mixed numbers will give percentages greater than 100.

• Taking a larger percentage and dividing by 100 will give you the decimal value which you will be able to convert to a fraction.

• Example:  485% = 4.85 = 4 $\frac{85}{100}$  = 4 $\frac{17}{20}$  

Smaller percentage values

•  $\frac{4}{100}$  This is 4% in fraction form.  The decimal will be 0.04.  Use your calculator to see this decimal value.

  
  

• The next slides will help you work on fraction to percentage or decimal to percentage problems.

Multiple Choice

Convert 102% to a decimal.

• 0.102

• 10.2

• 102

• Not here

Multiple Choice

Convert 0.78 to a percent.

• 78%

• 7.8%

• 0.78%

• Not here

Multiple Choice

Convert 6% into a decimal.

• 0.06

• 0.6

• 0.006

• 6

Multiple Choice

Convert 0.35 to a pecent.

• 35%

• 0.35%

• 3.5%

• 350%

Multiple Choice

Convert 1.5 to a percent.

• 15%

• 150%

• 1.5%

• 1500%

Multiple Choice

Convert 0.05 to a percent

• 50%

• 0.5%

• 500%

• 5%

Multiple Choice

Convert 25% to a decimal.

• 0.25

• 0.025

• 2.5

• 25

Multiple Choice

Convert 134% into a decimal.

• 0.134

• 1.34

• 0.0134

• Not here

Multiple Choice

dividing by 100 means the decimal moves...

• 2 places to the right

• 1 place to the left

• 1 place to the right

• 2 places to the left

Multiple Choice

multiplying by 100 means to move the decimal...

• 1 place to the left

• 1 place to the right

• 2 place to the right

• 2 places to the left

Multiple Choice

to turn a percent to a decimal you have to...

• subtract 100

• multiply by 100

• divide by 100

• add 100

Multiple Choice

to turn a decimal to a percent you need to...

• divide by 100

• multiply by 100

• subtract 100

• add 100

Multiple Choice

Change 198.7% to a decimal

• 19.87

• 1.987

• .1987

• 1987

Multiple Choice

Change 1.17 to a percent.

• 117%

• 1.17%

• 11.7%

• .117%

Multiple Choice

Change .98 to a percent.

• 98%

• 9.8%

• 980%

• .98%

Multiple Choice

Change 82% to a decimal.

• 82

• 8.2

• .82

• .082

Multiple Choice

Change .16 to a percent.

• 16%

• 1.6%

• 160%

• 0.16%

Multiple Choice

Change 32% to a decimal.

• 32

• .32

• 3.2

• .032

Multiple Choice

A dress is on sale for 40% off. Which decimal is equivalent to 40%?

• 0.04

• 0.40

• 40.00

• 4

Multiple Choice

Pizza Hut charges a 5% delivery fee. What decimal is equivalent to 5%?

• 0.5

• 0.05

• 5

• 0.005

Multiple Choice

Convert 8% to a decimal.

• 0.08

• 0.8

• 0.008

• 8