Understanding the concept
A discount reduces an original price by a stated percentage or fixed amount. Percentage discounts are calculated from the price to which they apply.
This lesson uses simple, fixed examples to explain the method. Identify the quantities, choose the correct formula, and check that the units in your answer make sense.
Sale price formula
Discount amount = original price × discount rate. Sale price = original price − discount amount.
Write down the original values before substituting numbers. Keep full precision during the calculation and round only when presenting the final result.
Worked example
Question: A jacket costs $120 and is reduced by 25%.
- Convert 25% to 0.25.
- Calculate the saving: 120 × 0.25 = 30.
- Subtract 120 − 30 = 90.
Check the answer against the original question. An answer should include the appropriate unit or percentage where relevant.
Key points to remember
- A 50% discount halves the price.
- Two successive 10% discounts do not equal a single 20% discount.
- Compare final checkout prices, including any delivery charges.
Common mistakes
Adding successive discount percentages together instead of applying them in order.
To avoid this, label each number, identify the starting amount and use a quick estimate to see whether the final answer is reasonable.
Try it yourself
A $60 item is reduced by 15%. What is the sale price?
Show the worked answer
Answer: 51. Try working through the method above before checking your result.
Sale-price shortcuts
Use this table as a quick reference. Check which quantities and units each method requires before calculating.
| Situation | Method or meaning | Calculation | Result |
|---|---|---|---|
| 10% off | Pay 90% of original price | $80 × 0.90 = $72 | $72 |
| 20% off | Pay 80% of original price | $80 × 0.80 = $64 | $64 |
| 25% off | Pay 75% of original price | $80 × 0.75 = $60 | $60 |
| 50% off | Pay half the original price | $80 × 0.50 = $40 | $40 |
More worked examples
Work through each calculation and notice how the method changes with the question.
Example 1: A $240 item is 30% off
Method: 240 × 0.70 = 168.
Example 2: A $150 item is 20% off, then 10% off
Method: 150 × 0.80 × 0.90 = 108.
Example 3: A $60 item has $15 off
Method: 60 − 15 = 45; 15 ÷ 60 × 100 = 25.
Using this in everyday life
Compare the final price, not just the advertised percentage. Delivery charges, minimum-spend conditions and exclusions may change which offer is better.
Before you begin: Identify what the question asks, write down the given information, use matching units, then estimate the result to catch mistakes.
Extra practice questions
Try these independently before expanding the answer. Show your working, not just the final number.
Question 1. 25% off $200
Show answer and working
200 × 0.75 = 150.
Answer: $150
Question 2. 15% off $80
Show answer and working
80 × 0.85 = 68.
Answer: $68
Question 3. 10% off $50 then another 10%
Show answer and working
50 × 0.9 × 0.9 = 40.50.
Answer: $40.50
Question 4. Saving on $120 reduced to $90
Show answer and working
120 − 90 = 30.
Answer: $30
Question 5. Discount rate from $100 to $65
Show answer and working
35 ÷ 100 × 100 = 35.
Answer: 35%