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Learning About Percent

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Learning About Percent
With Discounts Sales Tax and Tips %

How to use this tutorial
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.

Review Lesson Practice Home PAGE
Start with the review, then move on to the lesson. When you’re done, try the practice problems. Review Lesson Practice

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.

Now, it’s your turn … Review Example 1: Change 32% to a decimal 0.32
Example 2: Write 153% as a decimal 1.53 ANSWER ANSWER

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.

Let’s try these problems…
Review Let’s try these problems… Example 1: Change 0.86 to a percent 86% Example 2: Write 0.23 as a percent 23% ANSWER ANSWER

Great Work ! ! ! Now you’re ready for the LESSON

SALES! Discounts! Lesson
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 SALES! Discounts!

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 1 Discounts 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. You can calculate the discount by finding 20% of \$128. Click the arrow to find out how.

\$ 102.40 Example 1 Discounts \$25.60 1. 20% = 0.20 2. 128 x 0.20 =
STEPS 1. Change the percent to a decimal. 1. 20% = 0.20 2. Multiply this decimal by the regular price. Don’t forget to place the decimal in the right place in your answer. 1 1 2 8 x \$25.60 x 0.20 = 2 5 6 \$ 3. \$ –\$ = 3. Now to find the sale price, subtract the discount from the regular price. Ready for another example?

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.

\$ 117.00 Example 2 Discounts \$63.00 1. 35% = 0.35 2. 180 x 0.35 =
STEPS 1. Change the percent to a decimal. % = 0.35 2 2. Multiply this decimal by the regular price. Don’t forget to place the decimal in the right place in your answer. 4 1 8 x 3 5 \$63.00 x 0.35 = 9 1 + 5 4 6 3 3. Now to find the sale price, subtract the discount from the regular price. \$ 3. \$ –\$ = Let’s try one more.

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 \$ What is the sales price? You can calculate the discount by finding 75% of \$9.00. Click the arrow to find out how.

\$ 2.25 Example 3 Discounts \$6.75 1. 75% = 0.75 2. 9 x 0.75 =
STEPS 1. Change the percent to a decimal. 1. 75% = 0.75 2. Multiply this decimal by the regular price. Don’t forget to place the decimal in the right place in your answer. 6 4 7 5 x 9 \$6.75 2. 9 x 0.75 = 6 7 5 \$ 2.25 3. \$9.00 –\$ 6.75 = 3. Now to find the sale price, subtract the discount from the regular price. Not too hard, is it? Now, we can’t forget about sales tax! So click the arrow to learn how that’s calculated.

SALES TAX To find the amount of sales tax you need to:
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 In our cell phone example we found the sale price to be \$102.40 2. Multiply 0.06 by the cost of your item. Round your answer to the nearest hundredth. STEP 1 6% = 0.06 STEP 2 3. Add that amount to your original cost. 0.06 x = 6.144 This should be rounded to \$6.14 STEP 3 \$108.54 \$ \$6.14 = 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 In the telescope example we found the sale price to be \$117.00 2. Multiply 0.06 by the cost of your item. Round your answer to the nearest hundredth. STEP 1 6% = 0.06 STEP 2 3. Add that amount to your original cost. 0.06 x 117 = 7.02 STEP 3 \$124.02 \$117 + \$7.02 = This is the ACTUAL amount you would pay for the telescope.

\$2.39 SALES TAX Example 3 The calendar cost was \$2.25
1. Change the tax rate to a decimal. 6% = 0.06 The calendar cost was \$2.25 2. Multiply 0.06 by the cost of your item. Round your answer to the nearest hundredth. STEP 1 6% = 0.06 STEP 2 3. Add that amount to your original cost. 0.06 x 2.25 = 0.135 This can be rounded to 0.14 STEP 3 \$2.39 \$ \$0.14= 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 = \$4.70 Click for a shortcut. HERE

Click HERE for a reminder about using mental math
TipPING Example 1 Step 1 Change the percent to a decimal. 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. STEP 2 Multiply the percent by the total bill. Click HERE for a reminder about using mental math 15% = 0.15 0.15 x = 2.79 STEP 3 If needed, round to the nearest hundredth. \$2.79 is 15% of \$18.60

Click HERE for a reminder about using mental math
TipPING Example 2 Step 1 Change the percent to a decimal. A customer decides to leave a 20% tip for his dog groomer. The cost for the service was \$ What is the tip the customer leaves? STEP 2 Multiply the percent by the total bill. Click HERE for a reminder about using mental math 20% = 0.2 0.20 x 35 = 7 STEP 3 If needed, round to the nearest hundredth. \$7.00 is 20% of \$35.00

She tipped the driver \$4.86 TipPING Example 3
Step 1 Change the percent to a decimal. 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? STEP 2 Multiply the percent by the total bill. 18% = 0.18 0.18 x 27 = 4.86 STEP 3 If needed, round to the nearest hundredth. 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.

Now, you’re ready to practice some problems on your own.
Discount Problems Gratuity Problems

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! Great Work Way to Go

Wrong Answer Do you need ? YES NO

Here’s What to Do STEP 1 STEP 2 STEP 3
Back to the Problem STEP 1 25% = 0.25 Change the percent to a decimal. STEP 2 Multiply this decimal by the regular price. Don’t forget to place the decimal in the right place in your answer. 0.25 x 210 = STEP 3 Now to find the sale price, subtract the discount from the regular price. − =

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 Try Again Do you need ? YES NO

Here’s What to Do STEP 1 STEP 2 STEP 3
Back to the Problem STEP 1 20% = 0.2 Change the percent to a decimal. 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 29 = STEP 3 Now to find the sale price, subtract the discount from the regular price. 29.00 − 5.80 =

YES! The answer is \$23.20 GREAT WORK

Discount Problem 3 A necklace regularly sells for \$ 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 TARGET Good Work

Wrong Answer Check your work ! Do you need ? YES NO

Here’s What to Do STEP 1 STEP 2 STEP 3
Back to the Problem STEP 1 15% = 0.15 Change the percent to a decimal. STEP 2 Multiply this decimal by the regular price. Don’t forget to place the decimal in the right place in your answer. 0.15 x 18 = STEP 3 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 TRY AGAIN Do you need ? YES NO

Here’s What to Do STEP 1 STEP 2 STEP 3
Back to the Problem STEP 1 30% = 0.3 Change the percent to a decimal. STEP 2 Multiply this decimal by the regular price. Don’t forget to place the decimal in the right place in your answer. 0.3 x 30 = STEP 3 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! Great Work Way to Go

Wrong Answer Check your work ! Do you need ? YES NO

Here’s What to Do STEP 1 STEP 2 STEP 3 STEP 4 Back to the Problem
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 x 210 = ________ STEP 3 Now to find the sale price, subtract the discount from the regular price. – = _________ 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

Gratuity Problem 1 The cost of Ken’s car wash was \$ 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! Great Work Way to Go

Wrong Answer Do you need ? YES NO

Here’s What to Do STEP 1 STEP 2 STEP 3
Back to the Problem STEP 1 15% = 0.15 Change the percent to a decimal. STEP 2 Multiply this decimal by the regular price. Don’t forget to place the decimal in the right place in your answer. 0.15 x = STEP 3 Round your answer to the nearest hundredth and you get \$ Since this question asks about how much would you tip, you would give \$3.60.

Gratuity Problem 2 Constance got a manicure at the beauty shop. The cost for the manicure was \$ She left a 15% tip. How much money did she tip? \$1.70 \$3.83 \$5.10 \$38.25

Sorry Try Again Do you need ? YES NO

Here’s What to Do STEP 1 STEP 2 STEP 3
Back to the Problem STEP 1 15% = 0.15 Change the percent to a decimal. STEP 2 Multiply this decimal by the regular price. Don’t forget to place the decimal in the right place in your answer. 0.15 x = STEP 3 Now, round your answer to the nearest hundredth. \$3.83

YES! The answer is \$3.83 GREAT WORK

Gratuity 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 TARGET Good Work

Wrong Answer Check your work ! Do you need ? YES NO

Here’s What to Do STEP 1 STEP 2 STEP 3
Back to the Problem STEP 1 18% = 0.18 Change the percent to a decimal. STEP 2 Multiply this decimal by the regular price. Don’t forget to place the decimal in the right place in your answer. 0.18 x 7 = STEP 3 Now to find the TOTAL COST of the meal you need to add the tip amount to the cost of food. =

Gratuity Problem 4 A cab ride home cost 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 TRY AGAIN Do you need ? YES NO

Here’s What to Do STEP 1 STEP 2 Change the percent to a decimal.
Back to the Problem STEP 1 20% = 0.2 Change the percent to a decimal. 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 =

Gratuity 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 \$ How much will each person pay for the meal? \$8.88 \$11.10 \$13.32 \$12.65

You Got It! Great Work Way to Go

Wrong Answer Check your work ! Do you need ? YES NO

Here’s What to Do STEP 1 STEP 2 STEP 3 STEP 4 Back to the Problem
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 x = ________ STEP 3 Now to find the total price, add the tip to the bill. = _________ STEP 4 To find out how much each person should contribute, divide that total by 5. 66.60 ÷ 5 = __________

Easy! Move the decimal one place to the left.
Shortcut Easy! Move the decimal one place to the left. Use Mental Math 1. Find 10 % of your number by dividing the total by 10. 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 = \$5.10 That’s a great idea!

Easy! Move the decimal one place to the left.
Shortcut Use Mental Math Easy! Move the decimal one place to the left. 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. \$ \$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 Easy! Move the decimal one place to the left. 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 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.

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