Find how much something dropped, expressed as a percentage
The Formula
Percent Decrease = ((Original Value − New Value) / Original Value) × 100
Step 1: Subtract the new value from the original value (find how much it dropped). Step 2: Divide the drop by the original value. Step 3: Multiply by 100 to get the percent.
Examples
Example 1: A jacket was $120, now $90
Drop: $120 − $90 = $30
Divide by original: $30 ÷ $120 = 0.25
Multiply by 100: 0.25 × 100 = 25% decrease
Example 2: Weight went from 200 lbs to 180 lbs
Drop: 200 − 180 = 20
Divide by original: 20 ÷ 200 = 0.10
Multiply by 100: 0.10 × 100 = 10% decrease
Percent Decrease vs. Discount
When a store says "30% off," they're telling you the percent decrease. To find the sale price, you can either calculate the discount amount and subtract it, or multiply the original price by (1 − 0.30) = 0.70.
Shortcut for sale prices: If something is 30% off, you pay 70%. Multiply the price by 0.70.
$80 at 30% off → $80 × 0.70 = $56
💡 Remember: Just like percent increase, always divide by the original value — the starting point before the decrease.
🎯 Practice Problems
1. A TV was $500 and is now on sale for $400. What is the percent decrease?
A) 10%
B) 20%
C) 25%
D) 80%
2. Temperature dropped from 80°F to 60°F. What is the percent decrease?
A) 20%
B) 25%
C) 30%
D) 75%
3. A stock fell from $40 to $30. What is the percent decrease?
A) 10%
B) 25%
C) 30%
D) 75%
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🎯 Bonus Practice
1. A $60 item is 15% off. What do you pay?
A) $45
B) $51
C) $54
D) $9
2. Website traffic dropped from 10,000 to 7,500 visits. What is the percent decrease?
A) 75%
B) 25%
C) 35%
D) 2,500%
3. A car depreciated from $30,000 to $24,000. What is the percent decrease?
A) 6%
B) 20%
C) 24%
D) 80%
4. An item dropped from $200 to $100. What is the percent decrease?
A) 100%
B) 200%
C) 50%
D) half
5. A $90 shirt is 40% off. How much is the discount?