Percentages · Usually met around P6
Discounts
20% off = pay 80% of the price.
How to do it
Method
20% off = pay 80% of the price
$240 at 20% off: 240 × 80100 = 192
Another way
Find the amount off first
240 × 20100 = 48, 240 − 48 = 192
In full
A discount is a percentage taken off the price: 20% off means you pay the other 80%; 25% off means you pay 75%. Way 1: sale price = price × the percentage you pay, so $240 with 20% off → 240 × 80100 = $192. Way 2: find how much comes off, then take it from the price: 240 × 20100 = 48, 240 − 48 = $192, the same. Careful with two discounts one after the other: 20% off and then a further 10% off the reduced price is 80% × 90% = 72% of the price, which is 28% off, not 30%. To compare two offers, turn each into the percentage of the price you pay.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
An item's price is $460, and it is sold at 35% off. What is the sale price?
Show the answer and working
Answer: 299 dollars
35% off means paying 65%: 460 × 65100 = 299.
Example 2
An item's price was $120, and it now sells for $90. What percentage of the price is the sale price?
Show the answer and working
Answer: 75%
90 ÷ 120 × 100% = 75%, so it is 25% off.
Example 3
An item priced at $700 is sold at 30% off, so it is $210 cheaper.
True or false?
Show the answer and working
Answer: True
30% off means paying 70%, so 30% comes off: 700 × 30100 = 210.
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