Step by step
The question
Question: A shirt costs $40.
It is 25% off.
What is the sale price?
1 Find the discount
Percent means out of 100.
So 25% is 25 divided by 100: 0.25.
The point moves 2 places to the left.
25% = 25 ÷ 100 = 0.25
The discount is 25% of $40.
"Of" means times: 0.25 times $40.
That is $10.
discount = 0.25 × $40 = $10
To multiply decimals: first 25 times 40, as whole numbers.
That is 1000.
Then count the decimal places: 2.
So it is 10.00.
25 × 40 = 1000
2 decimal places: 10.00
Careful!
The discount is the money we save.
We still pay the rest.
Careful: $10 is what we save, not what we pay
2 Take it off
A discount comes off the price.
$40 minus $10 is $30.
sale price = $40 − $10 = $30
So the sale price is $30.
3 Check
Let's check another way: we pay 100% minus 25%: 75% of the price.
0.75 times $40 is $30.
The same.
So the answer is right!
100% − 25% = 75%: 0.75 × $40 = $30
Let's look back.
First: find the discount.
Then: take it off.
Last: check.
Answer
sale price = $40 − $10 = $30