The question
Question: A pair of shoes costs $60.
They are 15% off.
What is the sale price?
1 Find the discount
Percent means out of 100.
So 15% is 15 divided by 100: 0.15.
The point moves 2 places to the left.
15% = 15 ÷ 100 = 0.15
The discount is 15% of $60.
"Of" means times: 0.15 times $60.
That is $9.
discount = 0.15 × $60 = $9
To multiply decimals: first 15 times 60, as whole numbers.
That is 900.
Then count the decimal places: 2.
So it is 9.00.
15 × 60 = 900
2 decimal places: 9.00
Careful!
The discount is the money we save.
We still pay the rest.
Careful: $9 is what we save, not what we pay
2 Take it off
A discount comes off the price.
$60 minus $9 is $51.
sale price = $60 − $9 = $51
So the sale price is $51.
3 Check
Let's check another way: we pay 100% minus 15%: 85% of the price.
0.85 times $60 is $51.
The same.
So the answer is right!
100% − 15% = 85%: 0.85 × $60 = $51
Let's look back.
First: find the discount.
Then: take it off.
Last: check.
Answer sale price = $60 − $9 = $51
▶ Watch it solved
The question
Question: A lunch costs $36.
The tip is 18%.
What is the total cost?
1 Find the tip
Percent means out of 100.
So 18% is 18 divided by 100: 0.18.
The point moves 2 places to the left.
18% = 18 ÷ 100 = 0.18
The tip is 18% of $36.
"Of" means times: 0.18 times $36.
That is $6.48.
tip = 0.18 × $36 = $6.48
To multiply decimals: first 18 times 36, as whole numbers.
That is 648.
Then count the decimal places: 2.
So it is 6.48.
18 × 36 = 648
2 decimal places: 6.48
Careful!
18% is not $18.
It is 18% of the price.
Careful: not $36 + $18 = $54 ✗
2 Add it on
The tip is added to the price.
$36 plus $6.48 is $42.48.
total = $36 + $6.48 = $42.48
So the total is $42.48.
3 Check
Let's check another way: we pay 100% plus 18%: 118% of the price.
1.18 times $36 is $42.48.
The same.
So the answer is right!
100% + 18% = 118%: 1.18 × $36 = $42.48
Let's look back.
First: find the tip.
Then: add it on.
Last: check.
Answer total = $36 + $6.48 = $42.48
▶ Watch it solved
The question
Question: A jacket costs $80.
It is 25% off, then 8% sales tax is added.
What is the final 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 $80.
"Of" means times: 0.25 times $80.
That is $20.
discount = 0.25 × $80 = $20
To multiply decimals: first 25 times 80, as whole numbers.
That is 2000.
Then count the decimal places: 2.
So it is 20.00.
25 × 80 = 2000
2 decimal places: 20.00
Careful!
We can't just take 8% from 25%.
The tax is on the sale price, not on $80.
Careful: not 25% − 8% = 17% off: $66.40 ✗
2 Take it off
A discount comes off the price.
$80 minus $20 is $60.
sale price = $80 − $20 = $60
3 Find the tax
Percent means out of 100.
So 8% is 8 divided by 100: 0.08.
The point moves 2 places to the left.
8% = 8 ÷ 100 = 0.08
The tax is 8% of $60.
"Of" means times: 0.08 times $60.
That is $4.80.
tax = 0.08 × $60 = $4.80
To multiply decimals: first 8 times 60, as whole numbers.
That is 480.
Then count the decimal places: 2.
So it is 4.80.
8 × 60 = 480
2 decimal places: 4.80
4 Add it on
The tax is added to the price.
$60 plus $4.80 is $64.80.
total = $60 + $4.80 = $64.80
So the final price is $64.80.
5 Check
Let's check another way: we pay 100% minus 25%: 75% of the price.
0.75 times $80 is $60.
100% − 25% = 75%: 0.75 × $80 = $60
Then: we pay 100% plus 8%: 108% of the price.
1.08 times $60 is $64.80.
The same.
So the answer is right!
100% + 8% = 108%: 1.08 × $60 = $64.80
Let's look back.
First: find the discount.
Then: take it off.
Then: find the tax.
Then: add it on.
Last: check.
Answer total = $60 + $4.80 = $64.80
▶ Watch it solved
