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Multipliers

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					                Starter
                          3:5
               4:1
        9:7




              £64
                                1:7
17:15




               5:3
                      3:5
                4:1
         3:1




               £120
                            5:7
17 : 7




                5:3
                Multipliers
1. What do you multiply 3 by to make 12?
2. What do you multiply 4 by to make 36?

3. What do you multiply 6 by to make 15?
    Link between multiplication and division



12 ÷ 6 = 2              12 x ? = 2
35 ÷ 7 = 5              35 x ? = 5

       ÷ 6 is the same as x 1/6

Dividing by a number is the same as multiplying by its
                      inverse.
    To scale 6 to 15

                       15   To make 6 into 15;
                            ÷ 6 then x 15

                            This can be written
               X 15         as a fraction
6                                         15
                                          6
      ÷6
                            So the MULTIPLIER
           1                Is:
                                        15
                                         6
 To scale 10 to 4




10
                        What is the multiplier?



     ÷ 10           4
            X4


        1
     Find the multiplier in each question to
       scale from one number to another.


1.   5 to 12
2.   13 to 6
3.   15 to 8
4.   9 to 20
5.   100 to 140
      Using a multiplier in a table
       To find a missing entry, three related entries are
                           required.
     Find a pair of values you know and find the multiplier.
                                    An alternative way!
                                              x7


                                          5        35
x7          5      35         x7
 5                             5          7        n
            7      n

      n = 35 x 7/5                            x7
      n = 35 ÷ 5 x 7 = 49            n = 7 x 7 = 49
                 or
      n = 35 x 7 ÷ 5 = 49
                                             x7


x9         9      n           x9         9         n
 20       20     140           20
                                        20        140

                                             x7
      n = 140 x 9/20
      n = 140 ÷ 20 x 9 = 63         n = 9 x 7 = 63
                or
      n = 140 x 9 ÷ 20 = 63
4   n
9   54



8   88
5   n


7   140
n   120

4   84
n   105


4   22
n   33
                Plenary
      Complete the blanks in the table
SET A              SET B                 SET C

42                   6
105
                    24                   56
357

				
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posted:8/20/2010
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