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         ~=M-l&10._                                                                                                              ~=M•l&10._
                     PAGE  12                                                                                                                 PAGE  13

                    6                                                                                                            rn
                 12    8
                16~1~4
                    48
         a     24---- --a                                                                                                        Open: design sorting diagrams to
                 4' ~ \ 2                                                                                                        show the common factors (highest
                                                                                                                                 common factor to be ringed) of
         b  (1,48), (2,24), (3, 16), (4, 12), (6,8),                                                                             these pairs of numbers:
           (8,6), (12,4),  (16,3),  (24,4),  {48, 1)
                                                                                                                                 a

                                                                                                                                   Factors                  Factors
                                                                                                                                                        5
         a  Open: draw ray diagrams for six                                                                                         of 12                    of 20
           numbers between 20 and 50 and
           list their factor pairs.                                                                                              b
                                                                                                                                                            21
         Possible solutions:
                                                                                                                                   Factors                  Factors
         37: ( 1 ,37) (37' 1)
         25: ( 1 ,25) (5,5) (25, 1)                                                                                                 of 28   4                of 42
         46: ( 1 ,46) (2,23) (23,2) (46, 1)
         28: {1,28) {2,14) (4,7) (7,4) {14,2) {28,1)                                                                             c
         40: {1,40) (2,20) (4, 10) (5,8) (8,5) {10,4) (20,2) (40, 1)
         36: ( 1 ,36) (2, 18) (3, 12) (4, q) {6,6) {q ,4) ( 12,3) ( 18,2) (36, 1)   a  If you divide one number by another and the answer   Factors         Factors
                                                                          has no remainder on the calculator, both the divisor
         b  The factors of every number include 1 and the                                                                           of 15               7    of 35
                                                                          and the answer are factors of the original number.
           number itself. The number of factors of each
           number is even (with the exception of square                b  Open: design a different diagram to show the           d        24
           numbers).                                                      common factors (and highest common factor) of 65
                                                                          and q1.
                                                                                                                                  Factors                   Factors
         Challenge                                                        set of factors for 65 = {1,5, 13,65}                      of 24   8                of 36
                                                                          set of factors for q1  = {1,7, 13,q1}
         Practical: copy and complete a database for                      1 and 13 are common factors of 20 and 12
         numbers up to 25.                                                13 is the highest common factor of 20 and  12          e                      45
         Five numbers with odd numbers of factors:                                                                                                           5
         1, 4, q,  16, 25.                                             Challenge                                                  Factors                   Factors
         The numbers with odd number of factors are all                The completed diagram should give the following sets:        of 27                    of 45
         square numbers.                                               Factors of 35 {1, 5, 7, 35}
         Four other numbers less than  100 with odd number of          Factors of 63 {1, 3, 7, q,  21, 63}                       f
                                                                                                                                                          63
         factors: 36, 4q, 64, 81.                                      Factors of 54 {1, 2, 3, 6, q,  18, 27, 54}
                                                                                                                                  Factors                   Factors
                                                                                                                                    of 42               q    of 63
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