LEARNING ABOUT
PERCENT
With
Discounts
Sales Tax
and Tips
What is a StAIR?
A StAIR activity is a
stand alone
instructional resource.
This StAIR was created
for students to learn
more about finding the
percent of a number in
two real life situations:
sales tax and tipping.
After viewing the
instructional parts of
the power point,
students will work
through several practice
problems to
demonstrate their
understanding of the
skill.
HOW TO USE THIS TUTORIAL
Fractions, decimals, and percent are used
everywhere all around us. In this tutorial you
will practice calculating discounts and sale
prices and learn strategies for finding a tip.
Follow the directions
on each page to learn
more about how to find
the percent of a
number.
HOME PAGE
Start with the
review, then move
on to the lesson.
When you’re done,
try the practice
problems.
REVIEW
Remember … fractions, decimals, and percents are related. You can easily change
from a decimal to a percent or from a percent to a decimal.
When you are
changing a percent
to a decimal, divide
the percent by 100
and drop the percent
sign. Shortcut - just
move the decimal
two places to the
left! Look at the
table to see how it’s
done.
REVIEW
Now, it’s your turn …
Example 1: Change 32% to a decimal
0.32
Example 2: Write 153% as a decimal
1 .53
REVIEW
When you are
changing a decimal
to a percent,
multiply the number
by 100 and add a
percent sign.
Shortcut - move the
decimal two places
to the right. Here’s
what that looks like.
REVIEW
Let’s try these problems…
Example 1: Change 0.86 to a percent
86%
Example 2: Write 0.23 as a percent
23%
GREAT WORK
! ! !
Now you’re ready for the
Percent
Percent is
represented with the
% symbol. It is a
ratio that means out
of 100 or “per
hundred.”
15% = 15/100 = 0.15
25% = 25/100 = 0.25
LESSON
It’s important to know how to work with
percents when you are shopping so you can
find the cost of sale items and know what to
leave for a tip when you are provided a
service.
Let’s first talk about
Regular Price
The price of an item
before a discount.
This is sometimes
referred to as the
original price.
Discount
A discount is
calculated as a
percent of decrease.
E X A MP LE 1 DI SC OUN T S
Good news! The cell phone
you’ve always wanted has just
gone on sale. The regular price
of the phone is $128 and it’s
20% off.
Sale Price
The sale price is the
amount paid after a
discount is applied.
You can calculate the discount by finding 20% of $128.
Click the arrow to find out how.
EXAMPLE 1 DISCOUNTS
STEPS
1. Change the
percent to a
decimal.
2. Multiply this
decimal by the
regular price.
Don’t forget to
place the decimal
in the right place
in your answer.
3. Now to find the
sale price,
subtract the
discount from the
regular price.
1. 20% = 0.20
2. 128 x 0.20 =
1
1
2
8
x
0
2
2
3. $128.00 –$ 25.60 =
5
6
$ 102.40
Ready for another example?
$25.60
Regular Price
The price of an item
before a discount.
This is sometimes
referred to as the
original price.
Discount
A discount is
calculated as a
percent of decrease.
Sale Price
The sale price is the
amount paid after a
discount is applied.
EXAMPLE 2 DISCOUNTS
In a catalog you find a telescope
on sale for 35% off. The
original price is $180. How
much is the sale price?
You can calculate the discount by finding 35% of $180.
Click the arrow to find out how.
STEPS
1. Change the
percent to a
decimal.
2. Multiply this
decimal by the
regular price.
Don’t forget to
place the decimal
in the right place
in your answer.
3. Now to find the
sale price,
subtract the
discount from the
regular price.
EXAMPLE 2 DISCOUNTS
1. 35% = 0.35
2. 180 x 0.35 =
$180.00 –$ 63.00 =
Let’s try one more.
8
0
0
3
5
1
5
9
4
0
0
0
0
6
3
0
0
x
+
3.
2
4
1
$ 117.00
$63.00
Regular Price
The price of an item
before a discount.
This is sometimes
referred to as the
original price.
Discount
A discount is
calculated as a
percent of decrease.
Sale Price
The sale price is the
amount paid after a
discount is applied.
EXAMPLE 3 DISCOUNTS
On the clearance counter you
find a calendar marked 75% off.
The regular price of the
calendar was $9.00. What is
the sales price?
You can calculate the discount by finding 75% of $9.00.
Click the arrow to find out how.
EXAMPLE 3 DISCOUNTS
STEPS
1. Change the
percent to a
decimal.
2. Multiply this
decimal by the
regular price.
Don’t forget to
place the decimal
in the right place
in your answer.
3. Now to find the
sale price,
subtract the
discount from the
regular price.
1. 75% = 0.75
6
0
2. 9 x 0.75 =
x
6
3. $9.00 –$ 6.75 =
4
7
5
9
7
5
$ 2.25
Not too hard, is it? Now, we can’t
forget about sales tax! So click the
arrow to learn how that’s calculated.
$6.75
Sales Tax
Sales tax varies from
state to state. To
determine the
amount of sales tax
on an item you must
first know the tax
rate in your state. In
the state of Michigan
sales tax is 6%.
Sales tax is added to
the price of an item
at the point of
purchase.
SALES TAX
To find the amount of sales tax
you need to:
1. Change the percent to a decimal.
2. Multiply that by the cost of your item.
3. Finally, add that amount to the cost of your item.
For more information and examples about sales tax
click
.
HERE
SALES TAX EXAMPLE 1
1. Change the tax
rate to a decimal.
6% = 0.06
2. Multiply 0.06
by the cost of your
item. Round your
answer to the
nearest
hundredth.
3. Add that
amount to your
original cost.
In our cell phone example we found
the sale price to be $102.40
STEP 1
6% = 0.06
STEP 2
0.06 x 102.40 = 6.144
This should be rounded to $6.14
STEP 3
$102.40 + $6.14 =
$108.54
This is the ACTUAL amount you would pay for the cell phone.
SALES TAX EXAMPLE 2
1. Change the tax
rate to a decimal.
6% = 0.06
2. Multiply 0.06
by the cost of your
item. Round your
answer to the
nearest
hundredth.
3. Add that
amount to your
original cost.
In the telescope example we found
the sale price to be $117.00
STEP 1
6% = 0.06
STEP 2
0.06 x 117 = 7.02
STEP 3
$117 + $7.02 =
$124.02
This is the ACTUAL amount you would pay for the telescope.
SALES TAX EXAMPLE 3
1. Change the tax
rate to a decimal.
6% = 0.06
2. Multiply 0.06
by the cost of your
item. Round your
answer to the
nearest
hundredth.
3. Add that
amount to your
original cost.
The calendar cost was $2.25
STEP 1
6% = 0.06
STEP 2
0.06 x 2.25 = 0.135
This can be rounded to 0.14
STEP 3
$2.25 + $0.14=
$2.39
This is the ACTUAL amount you would pay for the calendar.
FOR MORE INSTRUCTION
Click Here
TIPPING
Tips
A tip or gratuity is
a small amount of
money left in
exchange for a
service. Tips are
calculated as a
percent of a price
just like sales tax.
It’s important to be able to figure out a tip
quickly. There are many circumstances
where this is needed …
 for the person who cuts your hair
 for servers at restaurants
 for the valet who retrieves your car
or for the taxi cab driver
TIPPING
Tips
A tip or gratuity is
a small amount of
money left in
exchange for a
service. Tips are
calculated as a
percent of a price
just like sales tax.
It is generally accepted that a tip should be between 15%
and 20% of the service provided.
The rule of thumb is 15% for adequate service and 20%
for exceptional service.
Here’s how it’s done …
To determine the tip, you need to change the percent to a
decimal and multiply by the cost of the service.
So, if your bill at the diner came to $23.50 and you had
exceptional service you would want to leave a 20% tip.
You would leave $4.70
20% = 0.2
0.2 x 23.50 = $4.70
Click
HERE
for a shortcut.
TIPPING EXAMPLE 1
Step 1
Change the
percent to a
decimal.
STEP 2
Multiply the
percent by the
total bill.
STEP 3
If needed, round to
the nearest
hundredth.
A customer wants to leave a 15% tip on a
bill for $18.60 at a Chinese restaurant. Find
out how much the customer should leave.
15% = 0.15
0.15 x 18.60 = 2.79
Click HERE for
a reminder
about using
mental math
$2.79 is 15% of $18.60
TIPPING EXAMPLE 2
Step 1
Change the
percent to a
decimal.
STEP 2
Multiply the
percent by the
total bill.
STEP 3
If needed, round to
the nearest
hundredth.
A customer decides to leave a 20% tip for his
dog groomer. The cost for the service was
$35.00. What is the tip the customer leaves?
20% = 0.2
0.20 x 35 = 7
Click HERE for
a reminder
about using
mental math
$7.00 is 20% of $35.00
TIPPING EXAMPLE 3
Step 1
Change the
percent to a
decimal.
STEP 2
Multiply the
percent by the
total bill.
STEP 3
If needed, round to
the nearest
hundredth.
Rachel gets a ride in a taxi from the airport.
The cab fare came to $27 and she decided
to tip the driver 18%. How much money did
she give to the driver?
18% = 0.18
0.18 x 27 = 4.86
She tipped the driver $4.86
VIDEO
Click on the attached video link to review what we learned
about solving percent problems with taxes and tips.
PRACTICE
Now, you’re
ready to practice
some problems
on your own.
DISCOUNT PROBLEM 1
Max found the bike that he’s wanted for a long
time on sale at 25% off. The original price of the
bike was $210. What is the price with the
discount?
$195.30
$142.50
$178.00
$157.50
You Got It!
Way to Go
WRONG ANSWER
Do you need
?
YE
S
NO
HERE’S WHAT TO DO
Back to
the
Problem
STEP 1
Change the percent to a decimal.
25% = 0.25
STEP 2
Multiply this decimal by the regular price. Don’t forget to
place the decimal in the right place in your answer.
STEP 3
0.25 x 210 =
Now to find the sale price, subtract the discount from the
regular price.
210.00 − 52.50 =
DISCOUNT PROBLEM 2
The bakery sells a dozen cupcakes for $29. To
celebrate their one year anniversary the owner is
selling all cupcakes for 20% off the regular price.
How much will it cost to buy a dozen cupcakes on
this day?
$23.20
$24.80
$28.52
$23.00
Sorry
Do you need
?
YE
S
NO
HERE’S WHAT TO DO
Back to
the
Problem
STEP 1
Change the percent to a decimal.
20% = 0.2
STEP 2
Multiply this decimal by the regular price. Don’t forget to
place the decimal in the right place in your answer.
STEP 3
0.2 x 29 =
Now to find the sale price, subtract the discount from the
regular price.
29.00 − 5.80 =
YES!
The answer is $23.20
DISCOUNT PROBLEM 3
A necklace regularly sells for $18.00. The store
advertises a 15% discount. What is the sale price
of the necklace in dollars?
$15.60
$16.70
$16.20
$15.30
RIGHT ON
Good Work
WRONG ANSWER
Do you need
?
YE
S
NO
HERE’S WHAT TO DO
Back to
the
Problem
STEP 1
Change the percent to a decimal.
15% = 0.15
STEP 2
Multiply this decimal by the regular price. Don’t forget to
place the decimal in the right place in your answer.
STEP 3
0.15 x 18 =
Now to find the sale price, subtract the discount from the
regular price.
18.00 − 2.70 =
DISCOUNT PROBLEM 4
A new radio is priced at $30. The store has an
end-of-year sale and all their items are 30% off.
What is the sale price of the radio?
$27.00
$21.00
$24.00
$9.00
You Got It!
Way to Go
WRONG ANSWER
Do you need
?
YE
S
NO
HERE’S WHAT TO DO
Back to
the
Problem
STEP 1
Change the percent to a decimal.
30% = 0.3
STEP 2
Multiply this decimal by the regular price. Don’t forget to
place the decimal in the right place in your answer.
STEP 3
0.3 x 30 =
Now to find the sale price, subtract the discount from the
regular price.
30.00 − 9.00 =
DISCOUNT PROBLEM 5
A chair that costs $210 was reduced by 40% for a
one-day sale. After the sale, the sale price was
increased by 40%. What is the price of the chair?
$176.40
$185.30
$205.50
$210.00
You Got It!
Way to Go
WRONG ANSWER
Do you need
?
YE
S
NO
HERE’S WHAT TO DO
Back to
the
Problem
STEP 1
Change the percent to a decimal. 40% = 0.4
STEP 2
Multiply this decimal by the regular price. Don’t forget to place the decimal in the
right place in your answer. 0.4 x 210 = ________
STEP 3
Now to find the sale price, subtract the discount from the regular price.
210.00 – 84.00 = _________
STEP 4
Now you have to find 40% of that sale price. So, $126 x 0.4 = _______. Then, add
that amount to $126.
FOR MORE PRACTICE
With problems involving discounts
Click Here
GRATUIT Y PROBLEM 1
The cost of Ken’s car wash was $23.95. If he
wants to give his detailer a 15% tip, about how
much of a tip should he leave?
$2.40
$3.60
$4.60
$4.80
You Got It!
Way to Go
WRONG ANSWER
Do you need
?
YE
S
NO
HERE’S WHAT TO DO
Back to
the
Problem
STEP 1
Change the percent to a decimal.
15% = 0.15
STEP 2
Multiply this decimal by the regular price. Don’t forget to
place the decimal in the right place in your answer.
STEP 3
0.15 x 23.95 =
Round your answer to the nearest hundredth and you get
$3.59. Since this question asks about how much would you tip,
you would give $3.60.
GRATUIT Y PROBLEM 2
Constance got a manicure at the beauty shop.
The cost for the manicure was $25.50. She left a
15% tip. How much money did she tip?
$1.70
$3.83
$5.10
$38.25
Sorry
Do you need
?
YE
S
NO
HERE’S WHAT TO DO
Back to
the
Problem
STEP 1
Change the percent to a decimal.
15% = 0.15
STEP 2
Multiply this decimal by the regular price. Don’t forget to
place the decimal in the right place in your answer.
STEP 3
0.15 x 25.50 =
Now, round your answer to the nearest hundredth.
$3.83
YES!
The answer is $3.83
GRATUIT Y PROBLEM 3
At a diner, Ruthie orders soup, salad, and a drink
that comes to $7. Find the total cost of the meal
if she leaves an 18% tip.
$8.18
$8.26
$1.26
$7.85
RIGHT ON
Good Work
WRONG ANSWER
Do you need
?
YE
S
NO
HERE’S WHAT TO DO
Back to
the
Problem
STEP 1
Change the percent to a decimal.
18% = 0.18
STEP 2
Multiply this decimal by the regular price. Don’t forget to
place the decimal in the right place in your answer.
STEP 3
0.18 x 7 =
Now to find the TOTAL COST of the meal you need to add the tip
amount to the cost of food.
1.26 + 7.00 =
GRATUIT Y PROBLEM 4
A cab ride home cost 16.40. Billy gave the driver
a 20% tip for his great service. How much money
did Billy give the cab driver?
$32.80
$1.64
$3.86
$3.28
You Got It!
Way to Go
WRONG ANSWER
Do you need
?
YE
S
NO
HERE’S WHAT TO DO
Back to
the
Problem
STEP 1
Change the percent to a decimal.
20% = 0.2
STEP 2
Multiply this decimal by the regular price. Don’t forget to
place the decimal in the right place in your answer.
0.2 x 16.40 =
GRATUIT Y PROBLEM 5
You and five friends go to lunch. You plan to split
the bill evenly, and you plan to leave a 20% tip.
The bill comes to $55.50. How much will each
person pay for the meal?
$8.88
$11.10
$13.32
$12.65
You Got It!
Way to Go
WRONG ANSWER
Do you need
?
YE
S
NO
HERE’S WHAT TO DO
Back to
the
Problem
STEP 1
Change the percent to a decimal. 20% = 0.2
STEP 2
Multiply this decimal by the regular price. Don’t forget to place the decimal in the
right place in your answer. 0.2 x 55.50 = ________
STEP 3
Now to find the total price, add the tip to the bill.
11.10 + 55.50 = _________
STEP 4
To find out how much each person should contribute, divide that total by 5.
66.60 ÷ 5 = __________
SHORTCUT
Use Mental Math
Easy! Move
the decimal
1. Find 10 % of your number by dividing the total by 10.
one place to
the left.
2. To find 20% just double that number since 20 % = 10% + 10%
If you are trying to figure out 15%, you just need to remember that
15% = 10% + 5%. If your bill was $34.00, 10% is $3.40, you can take half of that
number to find 5% . Half of $3.40 is $1.70 ( 3.40 ÷ 2 = 1.70). Now, just add this
together. 3.40 + 1.70 = $5.10
That’s a
great idea!
SHORTCUT
Use Mental Math
1. Find 10 % of your number by dividing the total by 10.
Moving the decimal one place to the left for $18.60
gives us $1.86
2. Remember 15% = 10% + 5%, so let’s find 5% now
5% is half of 10%. So, divide $1.86 in half and you get $0.93
3. Now, you just need to add these together.
$0.93 + $1.86 = $2.79
$2.79 is a 15% tip on $18.60
Easy! Move
the decimal
one place to
the left.
SHORTCUT
Use Mental Math
1. Find 10 % of your number by dividing the total by 10.
Moving the decimal one place to the left for $35.00
gives us $3.50
Easy! Move
the decimal
one place to
the left.
2. Since 20% = 10% + 10%, just double the answer you got in step 1.
$3.50 x 2 = $7.00
CONGRATULATIONS!
You’ve made it through
all the problems in this
tutorial. Now, you can
put these math skills to
good use the next time
you’re out shopping.