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					Please Turn Off Your Cell Phone!!!


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  answering the phone!


           Thank you for respecting your classmates!!!
       Section 8.2

Adding and Subtracting Decimal
         Expressions
 Adding + Subtracting Decimals


1. Rewrite so the numbers have the same
   amount of decimal places.
2. Line up the numbers’ decimal places
   vertically.
3. Add or subtract as normal.
               Example
Add: 40 + 8.77 + 0.9

                1
Ans:          40.00
               8.77
         +     0.90
              49.67  Answer
               You Try!!!
Add or Subtract:

1.   15 + 2.73 – 0.727

2.   -8.68 – 9.1
        Section 8.3

Multiplying and Dividing Decimals
      Multiplying Decimals


1. Multiply as normal
2. Add decimal places of original numbers
   to find decimal place of the result
                      Example
Multiply:           0.3 x 0.12

Ans:              3          Multiply as normal
             x   12
                 36

                    0.3      1 decimal place
                    0.12     2 decimal places

So, we need 3 decimal places for the result.

Thus, the answer is 0.036          3 decimal places
              You Try!!!

Multiply:

1.   0.13 × 12.1

2.   4.536 × 100
 Method: Dividing by Whole #


1. Place decimal point directly above
2. Divide as normal
           Example
Divide:
           33.6  6
Ans:
             5 .6
          6 33 .6
            30
             36
             36
              0
          You Try!!!
Divide:


          2.3  5
       Dividing by Decimal


1. Convert denominator (divisor) to whole
   number by moving decimal point to right
2. Move the numerator (+ result) to the right
   the same number of decimal points
3. Divide as normal
            Example
Divide:
            0.75 1.5
Ans:
             0.5
          15 7.5
             75
              0
          You Try!!!
Divide:


          5.12 1.6
Section 8.6

  Percents
            Def: Percents
Percent (symbolized as %) means “parts
 per hundred.”



Ex:

14 out of 100 students = 14% of students.
Method: Percents to decimals

• Percent  Decimal: Move decimal point 2
  places left + drop the %-symbol.

• Decimal  Percent: Move decimal point 2
  places right + add the %-symbol.
               Example
Convert 27.5% to a decimal.

Ans:

27.5% becomes 0.275
              You Try!!!


1.   Convert 1.1 to a percentage.



2.   Write 2.6% as a decimal.
                   Example
      211
Write        as a percent.
      500

Ans: First, we convert to a decimal:


    211                         211
         0.422          So,        42.2%
    500                         500
       Section 8.7

Solving Percent Problems using
          Equations
      Property: Percents
      amount = percent x base

Ex:        3 is 75% of 4

          (3) = (0.75)x(4)
              You Try!!!
1.   What is 25% of 40?



2.   10 is 25% of what number?



3.   36 is what percent of 90?
               You Try!!!
The new 8-mile nature trail is 125% of the
 length of the original trail. How long was
 the original trail?
           Complete IC11

• Spend the rest of the class completing the
  worksheet In-Class Exercises: Set 11.
• Feel free to work together in groups.
• Feel free to ask me questions.
• Feel free to have me check your work.
• Feel free to have me do example
  problems on the board.
       To Do for Next Week


• Read Sections 8.2-8.3, 8.6-8.7 in the book
• Check out Sections 8.8, 9.1-9.2 in the
  book
• MyMathLab Homework Set # 11
• Work on Exam 3

				
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