Percent Change - Percent Decrease

Students working on a math at a table.
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Percent increase and percent decrease are the two types of percent change. This article focuses on percent decrease.

What is Percent Decrease?

Percent decrease is a ratio that compares 2 values. It describes the decline in value of something by a specific rate. Percent decrease is evident anytime a number or amount decreases.

When is Percent Decrease Calculated in the Real World?

  • A school principal is comparing student attendance from one semester to another.
  • A cell phone company is comparing the number of February text messages to March text messages.

Example:  The original price for a bag of apples is $3. On Tuesday, the bag of apples sells for $1.80. What is the percent decrease?

Careful, do not find the difference between $3 and $1.80 and say that the percent decrease is $1.20.

Use this formula to find the percent decrease.

Percent decrease = (Older – Newer) ÷ Older.

= (3 – 1.80) ÷ 3

= .40 = 40%

Note: To convert a decimal into a percent, move the decimal point twice and stick a percent sign (%) at the end.

Percent Decrease is Given

In other situations, the percent decrease is known, but the newer value is unknown.

Example 1: Best Bargain wants to sell a laptop computer for $600 to Alan. J’s Electronics will sell the computer to Alan for 20% less than Best Bargain.

1. How much money will Alan save when he buys the computer from J’s Electronics instead of Best Bargain?


Multiply .20 and $600. Alan will save $120.

2. How much will Alan pay for the computer at J’s Electronics?
$600 – $120 = $480

Example 2:  A dress regularly sells for $150. A green tag, marked 40% off, is attached to the dress.

1. What is the discount? .40 * $150 = $60

2. What is the sale price? $150 - $60 = $90

Exercises

Answers and Explanations

1. A silk blouse regularly costs $45. It’s on sale for 33% off.
A. What is the discount?

B. What is the sale price?

 

2. A leather purse regularly costs $84. It’s on sale for 25% off.
A. What is the discount?

 

B. What is the sale price?

 

3. A scarf regularly costs $85. It’s on sale for 15% off.
A. What is the discount?

 

B. What is the sale price?

 

 

4. A sundress regularly costs $30. It’s on sale for 10% off.
A. What is the discount?

 

B. What is the sale price?

 

 

5. A women’s silk romper regularly costs $250. It’s on sale for 40% off.
A. What is the discount?

 

B. What is the sale price?

 

 

6. A pair of women’s platform heels regularly costs $90. It’s on sale for 60% off.
A. What is the discount?

 

B. What is the sale price?

 

 

7. A floral skirt regularly costs $240. It’s on sale for 50% off.
A. What is the discount?

 

B. What is the sale price?