b) percent shortcuts

7/28/2019 b) Percent Shortcuts

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WARM UP # 8:Fractions, Decimals & PercentWrite each fraction as a decimal and percent.

Fraction Decimal Percent1) 1/32) 3/4

3)1/8

4)7/10

5) 7/96) 3/57) 2

/3

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out

a

Calculator!


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Correct Homework If you did not write your full name, date,

and period on your paper take off 1 point. If you did NOT write each problem -3

points! If you did NOT write the work next to

each problem -3 points! Take off 1 point for each problem not

done. Put your score on your paper out of 10.


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Percent

Shortcuts


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Method 1:Use place value.

0.2 = 210

20100

=

Method 2: Multiply by 100

*Move the decimal 2 placesto the right.

0.2 = 0.20 = 20%

= 20%

218% =

218

100 = 218 100 = 2.18

20% =20

100= 20 100 = 0.20

Divide by 100 *Move the decimal 2 places to the left.


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Method 1: Write an equivalent fraction with a

denominator of 100.

2

5 x20

x20=

40

100= 40%

Method 2: Write the fraction as a decimal.

2

5= 2 5 = .40 = 40%

52% =52

100

4

4=

13

25

Put the percent over

100 and reduce.


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DECIMALS ANSWER DECIMALS ANSWER

0.3 0.861

0.41 0.35

1.13 0.001131100

41

100

3

10

861

1000

35

100

1

1000

1)

2)

3)

4)

5)

6)


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FRACTIONS ANSWER FRACTIONS ANSWER

0.625 0.18

0.1875 1.5

0.5 0.6

5

8

3

16

5

10

2

11

1)

2)

3)

9

63

5

4)

5)

6)


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PERCENTS ANSWER PERCENTS ANSWER

1) 50% 4) 3%

2) 29% 5) 37.5%

3) 129% 6) 25%

50 1

100 2

3

100

29

100

129 29

100 1001

37.5 375 3

100 1000 8

25 1

100 4


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Fraction Decimal Percent45

0.8 80%

16

1000.16 16%

9

10000.009 0.9%

4

25


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Fraction Decimal Percent7

1000.07 7%

3

100.3 30%

27

102.7 270%


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2 = 50%1


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4 = 25%1


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4 = 75%3


14/32

3 = 33.3%1


15/32

3 = 66.6%2


16/32

5 = 20%1


17/32

5 = 40%2


18/32

5 = 60%3


19/32

5 = 80%4


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Find 17% of 30010% of 300 =

5% of 300 =

1% of 300 =

1% of 300 =+

17%of 300= 51

30030

153003

3


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Lindsey was given lots of problems.All of them required that she find

various percents of $200.

Lindsey made a table to help her

organize her data.

She used benchmarks to help hersolve each percent problem.


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BENCHMARKS are common numbersthat serve as points of reference.

If you know yourBENCHMARKSthen you can easily calculate harder

percent problems by combining

BENCHMARKnumbers together.

Just watch!


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1. What is 50% of 200? ____

2. What is 25% of 200? ___

3. What is 10% of 200? ____

4. What is 5% of 200? ____

5. What is 1% of 200? ____

100

50

20

10

2

1) 6% of 200 ______12

6% = 5% + 1%

= 10 + 2


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1. What is 50% of 200? ____

2. What is 25% of 200? ___

3. What is 10% of 200? ____

4. What is 5% of 200? ____

5. What is 1% of 200? ____

100

50

20

10

2

2) 9% of 200 ______18

9% = 10%1%

= 20 2


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1. What is 50% of 200? ____

2. What is 25% of 200? ___

3. What is 10% of 200? ____

4. What is 5% of 200? ____

5. What is 1% of 200? ____

100

50

20

10

2

3) 23% of 200 ______46

23% =

20% + 1% + 1% + 1%or

25% 1% 1%

= 50 2 2


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1. What is 50% of 200? ____

2. What is 25% of 200? ___

3. What is 10% of 200? ____

4. What is 5% of 200? ____

5. What is 1% of 200? ____

100

50

20

10

2

4) 41% of 200 ______82

41% =

50%

10% + 1%

=10020 + 2

Or.41% =25% + 10% + 5% + 1%


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Take out your

study guide

please.


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1

20=5%

#4

0.05 =

1

10=10% 0.1 =

1

5

=20% 0.2 =

1

4=25% 0.25 =

1

3=33.3% 0.3 =

1

2

=50% 0.5 =

2

3

=66.6% 0.6 =

3

4=75% 0.75 =


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#5

1. What is 50% of 500? ____2. What is 25% of 500? ____

3. What is 10% of 500? ____

4. What is 5% of 500? ____

5. What is 1% of 500? ____

250

125

50255

1) 8% of 500

= 40

8% =10%2%

=5010

2) 61% of 500

= 305

61% =50% + 10% + 1%

= 250 + 50 + 5


31/32

Estimate21% of 66

21% 20% Use a benchmark close to 21%.

1

5 Write 20% as a fraction.

66 65

1

5 65 =

So 21% of 66 isabout 13.

#6

20%

Use compatible numbers.

Use mental math: 65 5.13


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Name___________

January 21, 2010

Period___

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