2. Chapter 6 Lesson 6 Finding Percents Mentally Pgs. 293-297 What you will learn: Compute mentally with percents Estimate with percents What you will learn: Compute mentally with percents Estimate with percents

3. This is a table that would be a good thing to memorize!!  Concept Summary: %-Fraction Equivalents 20%= 1 5 10%= 1 10 25%=1 4 12 % = 1 8 16 % = 1 6 40%=2 5 30%=3 10 50%=1 2 37 %= 3 8 33 % = 1 3 60%=3 5 70%=7 10 75%=3 4 62 % = 5 8 66 %= 2 3 80%=4 5 90%=9 10 87 % = 7 8 83 % = 5 6 1212 1212 1212 1212 2323 1313 2323 1313

4. Example 1: Find Percent of a Number Mentally Find the percent of each number mentally. A.50% of 28 50% of 28 = 1/2 of 28 Think: 50% = 1/2 = 14 Think: 1/2 of 28 is 14 So, 50% of 28 is 14 Find the percent of each number mentally. A.50% of 28 50% of 28 = 1/2 of 28 Think: 50% = 1/2 = 14 Think: 1/2 of 28 is 14 So, 50% of 28 is 14

5. Example 1 Continued Find the percent of each number mentally. B.25% of 36 25% of 36 = 1/4 of 36 Think: 25% = 1/4 = 9 Think: 1/4 of 36 is 9 So, 25% of 36 is 9 C.40% of 55 40% of 55 = 2/5 of 55 Think: 40% = 2/5 = 22 Think: 1/5 of 55 is 11. So, 2/5 of 55 is 22 Find the percent of each number mentally. B.25% of 36 25% of 36 = 1/4 of 36 Think: 25% = 1/4 = 9 Think: 1/4 of 36 is 9 So, 25% of 36 is 9 C.40% of 55 40% of 55 = 2/5 of 55 Think: 40% = 2/5 = 22 Think: 1/5 of 55 is 11. So, 2/5 of 55 is 22

6. Example 2: Estimate Percents A.Estimate 13% of 160. 13% is about 12.5% or 1/8 1/8 of 160 is 20. So, 13% of 160 is about 20 B. Estimate 80% of 296 80% is equal to 4/5 296 is about 300 4/5 of 300 is 240 So, 80% of 296 is about 240. A.Estimate 13% of 160. 13% is about 12.5% or 1/8 1/8 of 160 is 20. So, 13% of 160 is about 20 B. Estimate 80% of 296 80% is equal to 4/5 296 is about 300 4/5 of 300 is 240 So, 80% of 296 is about 240.

7. Example 2: Continued C.Estimate 1/5% of 39 1/5% = 1/5 x 1%. 39 is about 40 1% of 40 is.4 So, 1/5% of 39 is about 1/5 x.4 or.08 D.Estimate 295% of 145 295% means about 300 for every 100 or about 30 for every 10. 145 has one 100 and about 5 tens. (300*1) + (30*5) = 300 + 150 or 450 So, 295% of 145 is about 450 C.Estimate 1/5% of 39 1/5% = 1/5 x 1%. 39 is about 40 1% of 40 is.4 So, 1/5% of 39 is about 1/5 x.4 or.08 D.Estimate 295% of 145 295% means about 300 for every 100 or about 30 for every 10. 145 has one 100 and about 5 tens. (300*1) + (30*5) = 300 + 150 or 450 So, 295% of 145 is about 450

8. Example 3: Use Estimation to Solve a Problem Sally wants to leave a tip of 15% on a dinner check of $52.48. About how much should she leave? $52.48 is about $50. 15% = 10% + 5% 10% of $50 is $5.00 Move the decimal one place left 5% of $50 is $2.50 5% is one half of 10% So, 15% is about $5.00 + $2.50 or $7.50 A reasonable amount for the tip would be $8. Sally wants to leave a tip of 15% on a dinner check of $52.48. About how much should she leave? $52.48 is about $50. 15% = 10% + 5% 10% of $50 is $5.00 Move the decimal one place left 5% of $50 is $2.50 5% is one half of 10% So, 15% is about $5.00 + $2.50 or $7.50 A reasonable amount for the tip would be $8.

9. Your Turn! Find the percent mentally A.75% of 16 B.66 % of $24 C.125% of 300 D.20% of 105 A.75% of 16 B.66 % of $24 C.125% of 300 D.20% of 105 2323 75% = 3/4 3/4 of 16 is 12 66 2/3 = 2/3 2/3 of 24 is 16 So, $16 This means 125 for every 100 Or 12.5 for every 10. 300 has 30 tens So, 12.5 x 30 = 375 20% = 10% + 10% 10% of 105 = 10.5 So, 10.5 + 10.5 = 21

10. Practice Makes Perfect! Extra practice is by the door on your way out! Have a Great Weekend! Extra practice is by the door on your way out! Have a Great Weekend!