Decimals mult dividing xo9c5w by 5ci9M3

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									      Decimals

Multiplication and Division
      What is to be learned?
• How to multiply decimals by any number
• How to divide decimals by any number
   Multiplying and Dividing
4.12 X 3
              .
             4.12
             X 3
            12 36

8.48 ÷ 4
               2 12
                .
             4 8.48
     Multiplying/Dividing Decimals

Steps to success
                               Don’t
Multiply/Divide as Normal      forget
Put decimal point in answer    Me!

Check decimal points are in a line
              .
             3.4
            X 2
             68
            The Test of Success
What is to be learned?   Steps to success
How to multiply/divide   Multiply/Divide as normal
decimals
                         Put Decimal Point in Answer

 5.31 X 4                Check decimal points are in
                          a line

                .
               5.31
               X4
              21 24
       What is to be learned
• How to multiply decimals by 10 and 100
• How to divide decimals by 10 and 100
 A wee problem
10 X 13 = 130

10 X 1.3 = 1.30
               Multiplying by 10



0                                       1
    0.1

          0.1 X 10 = 1.0

           .
          0 1 0            point moves one
                           place to right
               X10
3.56 X 10
         35.6
15.78 X 10
         157.8
2.3 X 10
         23 (23.0)
              Multiplying by 100

Point moves two places to right

2.789 X 100
                   278.9
3.56 X 100
                   356 (356.0)
          Wee Problem
           3.2 X 100


                 X 100

same as    X 10     X 10


   3.2    X 10     32    X 10   320
                   You Try

1.   4.56 X 10         45.6
2.   3.4 X 10          34
3.   0.34 X 10         3.4
4.   2.678 X 100       267.8
5.   3.56 X 100        356
6.   3.4 X 100         340
7.   0.5 X 100         50
    Multiplying Decimals by 10,100

Steps to success
X10
move point one place to right
X100
multiply by 10 twice


5.83 X 10 = 58.3
3.7 X 100
3.7 X 10 = 37 X 10 = 370
             The Test of Success
 What is to be learned?    Steps to success
How to multiply decimals   X10
by 10 and 100              move point one place to right
                           X100
                           multiply by 10 twice

     5.6 X 10 = 56 (or 56.0)
     3.7 X 100 = 370
             Dividing by 10

Point moves one places to left

43.2 ÷ 10
                  4.32
348.9 ÷ 10
                  34.89
  More Difficult
42.0 ÷ 10
            4.2 (or 4.20)
236 ÷ 10
            23.6
1.56
            0 .156
              Dividing by 100
                       ÷ 100

     same as       ÷ 10    ÷ 10

435.6 ÷ 100
                   4.356
48.9 ÷ 100
                   0.489
362 ÷ 100
                   3.62
      Dividing Decimals by 10,100

Steps to success
÷ 10
move point one place to left
(put .0 if necessary)
÷ 100
divide by 10 twice

62.0 ÷ 10 = 6.2 (or 6.20)
45.83 ÷ 100
45.83 ÷ 10 = 4.583 ÷ 10 = 0 .4583
             The Test of Success
 What is to be learned?     Steps to success
How to divide decimals by   ÷10
10 and 100                  move point one place to left
                            (put .0 if necessary)
                            ÷100
                            divide by 10 twice
     8 ÷ 10 = 0.8
     2.6 ÷ 100 = 0.026

								
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