1. Today’s Lesson: What: mental percentages and the percent proportion Why: To solve several different types of percentage problems using both mental math and the percent proportion formula. What: mental percentages and the percent proportion Why: To solve several different types of percentage problems using both mental math and the percent proportion formula.

2. How to compute percentages using the power of your mind ( who needs a calculator anyway ???): PercentageHow do I do it???Example(s) 10% Slide the decimal ONE to the left! 10% of 5,280 = 528 1% Slide the decimal TWO to the left! 1% of 400 = 4 20% Find 10%-- then DOUBLE it!! 20% of 70 = 14 * Since 10% is 7, we double 7 to get 14! 5% Find 10%-- then cut it in HALF!! 5% of 48 = 2.4 * Since 10% is 4.8, we take half of that number, which is 2.4! 15% Find 10%, find 5%-- ADD them together!! 15% of 40 = 6 * Since 10% is 4 and 5% is 2-- add 4 and 2 to get 6! 50% Cut the number in HALF!!50% of 82 = 41 * Since 41 is HALF of 82! 25% Find 50%-- then cut it in HALF!! 25% of 18 = 4.5 * Since 50% of 18 is 9, we take half of 9 !

3. Find 10% of... 1. 800 = _____2. 255 = _____ You try... 5. 2,500 = _____6. 48.89 = _____ 3. 2.23 = _____4. 32.5 = _____ 7. 199.9 = _____8.2,527 = _____ 80 25 0.2233.25 2504.889 19.99 252.7

4. Miscellaneous... 1. 20% of 90 2. 20% of 420 3. 5% of 440 4. 5% of 82 5. 15% of 80 6. 15% of 1,000 7. 1% of 325.5 8. 1% of 8 9. 50% of 70 10. 50% of $6.24 11. 25% of 20 12. 25% of 4.40 1884 22 4.1 12 1503.2550.08 35 $3.125 1.10

5. % part “is” 100 whole “of” = We can use the above formula to solve ANY type of percentage problem. WHY??? Because, using this formula allows us to find the missing percentage, find the missing part, or find the missing _________________________. We place _________ in the correct position, according to what we need to find. The Percent proportion formula... whole x

6. Solving for the percent... Solving for the part... Solving for the whole...

7. % part “is” 100 whole “of” = Real-Life Scenarios: 1) Collin scored an 88% on the test. If there were 40 total questions, how many did Collin answer correctly? x ≈ 35 questions

8. % part “is” 100 whole “of” = 2)Jane scored a 94% on the test. If she answered 47 questions correctly, how many total questions were on the test? x = 50 questions

9. % part “is” 100 whole “of” = 3)On the Unit 8 Test, Holly got 40 questions correct out of 45 total questions. What was her percentage score? x ≈ 89%

10. % part “is” 100 whole “of” = 4)Hannah made $40 from babysitting. She spends $8 at the dollar store. What percent of her babysitting money did she spend? x = 20%

11. % part “is” 100 whole “of” = 5) Henry earned $45 mowing lawns. This is 25% of his total savings. What is his total savings? x = $180

12. % part “is” 100 whole “of” = 6) Callie spent 30% of her savings on an i-Pod. If the i-Pod was $120, how much did she have in savings to begin with? x = $400

13. END OF LESSON The next slides are student copies of the notes for this lesson. These notes were handed out in class and filled-in as the lesson progressed. NOTE: The last slide(s) in any lesson slideshow (entitled “Practice Work”) represent the homework assigned for that day.

14. Math-7 NOTES DATE: ______/_______/_______ What: mental percentages and the percent proportion Why: To solve several different types of percentage problems using both mental math and the percent proportion formula. What: mental percentages and the percent proportion Why: To solve several different types of percentage problems using both mental math and the percent proportion formula. NAME: How to compute percentages using the power of your mind :( who needs a calculator anyway ???) PercentageHow do I do it???Example(s) 10%Slide the decimal ONE to the left! 10% of 5,280 = 528 10% of $423.74 = $42.37 1%Slide the decimal TWO to the left!1% of 400 = 4 20%Find 10%-- then DOUBLE it!!20% of 70 = 14 * Since 10% is 7, we double 7 to get 14 ! 5%Find 10%-- then cut it in HALF!!5% of 48 = 2.4 * Since 10% is 4.8, we take half of that number, which is 2.4 ! 15%Find 10%, find 5%-- ADD them together!! 15% of 40 = 6 * Since 10% is 4 and 5% is 2-- add 4 and 2 to get 6 ! 50%Cut the number in HALF!!50% of 82 = 41 * Since 41 is HALF of 82 ! 25%Find 50%-- then cut it in HALF!!25% of 18 = 4.5 * Since 50% of 18 is 9, we take half of 9 ! Find 10% of... 1. 800 = _____2. 255 = _____3. 2.23 = _____4.32.5 = _____ 5. 2,500 = _____6. 48.89 = _____7. 199.9 = _____8.2,527 = _____ You try...

15. % part “is” 100 whole “of” = Miscellaneous... 1.20% of 902. 20% of 4203. 5% of 4404. 5% of 82 5. 15% of 806. 15% of 1,0007. 1% of 325.58.1% of 8 9. 50% of 70 10. 50% of $6.2411. 25% of 2012. 25% of $4.40 The Percent proportion formula... Solving for the percent... Solving for the part... Solving for the whole...

16. % part “is” 100 whole “of” = Real-Life Scenarios: 1)Collin scored an 88% on the test. If there were 40 total questions, how many did Collin answer correctly? 2)Jane scored a 94% on the test. If she answered 47 questions correctly, how many total questions were on the test? 3)On the Unit 8 Test, Holly got 40 questions correct out of 45 total questions. What was her percentage score? 4)Hannah made $40 from babysitting. She spends $8 at the dollar store. What percent of her babysitting money did she spend? 5)Henry earned $45 mowing lawns. This is 25% of his total savings. What is his total savings? 6)Callie spent 30% of her savings on an iPod. If the i-Pod was $120, how much did she have in savings to begin with?

17. Fill in the missing spaces in the below charts by using the mental math strategies from your notes (do not use a calculator): DATE: ______/_______/_______NAME:____________________________________________________________________________ 508.42804,080 10% 5% 15% 20% 25% 42.6160240.890 10% 5% 15% 20% 25% Miscellaneous... 1.20% of 252. 10% of 1,2483. 5% of 64. 10% of 22.8 5. 15% of 8226. 1% of 2.77. 25% of 208.50% of 500

18. Use the Percent Proportion Formula to answer the following (some do not work out evenly– round to the nearest tenth unless otherwise specified) : DATE: ______/_______/_______NAME:____________________________________________________________________________ 1) Bridget scored a 95% on the test. If there were 40 questions, how many did she answer correctly? 2) Zack scored a 92% on the test. If he answered 23 questions correctly, how many total questions were on the test? 3) Linda got 33 questions correct out of 40 total questions on the test. What is her percentage score (round to the nearest whole percent)? 4) Nate had $50 in his piggy bank. He took $22 out in order to buy some headphones. What percent of his original total did he take out? 5)Sandy withdrew 34% of her savings. If she withdrew $120, how much was in her savings to begin with? 6)Kelly spent 60% of her paycheck at Target. If her paycheck was $300, how much did she spend?