**Mental Percents**

**Lesson 3**

- Start the lesson with a question to the students using a tipping situation in a restaurant.
- What is the appropriate tipping % in a restaurant? (15%, 17%, 20%)
- If your bill is $52.78, how would you go about tipping 15%? (Make sure all calculators, pens, pencils, etc. are not being used for maximum effect)

- Allow students some time to think out the solution. Question several students on their thought processes.
- Educate students on the 10% rule using the following examples:
- $3.00
- $18.00
- $54.65
- $123.45…etc.

- Now go back to the original problem.
- First round to the nearest whole dollar.
- Then find 10%.
- Round again if necessary

- Then find half of 10% (which is 5%)
- Round again if necessary
- Add the two together and you have your approximate tip.

- Go through process again using the amount $44.80
- Give the students one minute to try.
- Go through steps above until you arrive at your answer.

- Do as many examples as necessary until you feel the class has confidence in doing them on their own.

- Store sales
- What are some of the common sales you see in retail or department stores?
- Are the markdowns on the merchandise or at the register?
- How do you know if you are getting the correct discount?

- Share a few personal stories here.

- Situation 1: The store has a 30% off sale and the item you are buying is marked at $35.99. What should your discount be?

- See if students apply the 10% rule to the problem.
- Round the amount to $36.00
- Take 10% by moving the decimal one place left.
- Round if you need to the nearest dollar.
- Then multiply by 3 and you have your discount.
- Explain that 3 x 10% = 30%.
- Do another 30% problem if necessary.

- Situation 2: The store has a 60% off sale and the item you are buying is marked at $74.25. Find the approximate discount.

- Go through the same steps above except this time show students that 6 x 10% is 60%.
- Do another if necessary.

- Situation 3: The store has a 50% off sale, but today you save an additional 25%.

- Ask the students if this means they will save 75% total?
- Go through the following steps and see.
- First find 50% off (Either half off or 5 x 10%)
- Then take 25% off that amount (either one fourth of the amount or go through steps like a tip: Find 20% and then add half of 10% to it)
- Then take the original amount and find 75% off. (Some students can do fourths, some will find 70% and 80% and determine the number in the middle, and lastly some will find 70% and add 5% to it. Anything mathematically correct is acceptable when doing mental percents)
- The discount found from step 2 will be less than that found in step 3. Discuss why.

- If a store has a sale 75% off, plus additional 20% off, plus and additional 5% off if you use your store credit card, will that mean you get it for free?

- Can your store purchase ever come out to free?
- Have students research the Sunday paper over the next few weeks for sales that have these types of advertisements in them.

Main Course Description Student Lesson 1 Student Lesson 2 Student Lesson 3 |