Page 215 - ICSE Math 4
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2.  (a)  2, 4 and 6   (b)  4 and 14   (c)  6 and 3  Exercise 7.4
                        (d)  5         (e) 4 and 2                        1.  (a), (b), (e) and (f)   2.  (b), (c), (e) and (f)
                      3. Yes                  4. Yes                      3.  (a), (b) and (e)    4.  (a), (b), (e) and (f)
                      5.  (a)  1, 2 and 4    (b)  1 and 3                 5.  (a), (b) and (d)    6.  (a), (b) and (e)
                         (c)  1 and 2        (d)  1, 2, 4, 5 and 20
                                                                        Exercise 7.5
                    Exercise 7.2                                          1.  (a)  2   (b) 9   (c)  3   (d) 14  (e)  9   (f) 2
                     1.  (a)  mul  ple       (b)  greater than           2.  12
                                                                          3.  (a)  6, 12, 18, 24, 30; 6   (b)  15, 30, 45, 60, 75; 15
                         (c)  9, 18, 27, 36, 45, 54, 63, 72 and 81
                        (d) infi nite                                         (c)  120, 240, 360, 480, 600; 120
                                                                             (d)  60, 120, 180, 240, 300; 60
                      2.  (a)  7, 14, 21, 28, 35   (b)  11, 22, 33, 44, 55
                         (c)  14, 28, 42, 56, 70   (d)  8, 16, 24, 32, 40       (e)  48, 96, 144, 192, 240; 48
                                                                             (f)  150, 300, 450, 600, 750; 150
                         (e)  6, 12, 18, 24, 30
                      3. (a)  48; 84   (b) 72; 126     (c) 16; 28         4.  (a)  9   (b) 48  (c)  24  (d) 10  (e)  12   (f) 180
                        (d)  64; 112   (e) 20; 35                       Review Exercise
                      4.  (a)  24, 650 and 418   (b)  65 and 950          1.  (a)  even   (b) 1    (c) 47     (d) 2
                         (c)  72 and 615     (d)  81 and 18                 (e) smallest (f) 5, 10 and 15 (g) composite
                      5.  (a)  21 and 42   (b)  16 and 64   (c)  18 and 36    2.  (a)  (iii)   (b) (ii)   (c) (iv)   (d) (ii)   (e) (ii)
                         (Answers may vary)                               3.  (a)  2, 3; 2, 5
                                                                             (b)  (i)  2, 6, 7, 21 and 42   (ii)  2, 3, 4, 6 and 12
                    Exercise 7.3
                                                                                (iii)  1, 2, 4, 7 and 14   (iv)  2, 5, 10, 25 and 50
                      1.  (a)  2; 3   (b) 4   (c) even    (d) 0; 1
                                                                              (Answers may vary)
                         (e) 2; 5   (f) two   (g) 25      (h) 2; 3
                                                                             (c)  (i)  13, 39, 65, 91, 117   (ii)  9, 27, 45, 63, 81
                        (i) Prime factoriza  on
                                                                                (iii)  17, 51, 85, 119, 153  (iv)  21, 63, 105, 147, 189
                     2.  (a)  21 ,  27 , 30,  39 , 42,  45
                                                                             (d)  (i)  52 = 2 × 2 × 13   (ii)  124 = 2 × 2 × 31
                         (b)  24, 28, 32, 36, 40, 44
                                                                                (iii)  17 = 1 × 17   (iv)  147 = 3 × 7 × 7
                        (c) 25 , 30,  35 , 40,  45 , 50
                                                                             (e)  Yes, 248 is a mul  ple of 4.
                         (d)  24, 30, 36, 42, 48, 54
                                                                             (f)  Yes, 12 is a factor of 2,460.
                      3.  2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47
                                                                             (g)  Students to do on their own.
                      4.   32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50,     4.  (a)  8   (b) 11   (c) 2   (d) 24
                        51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69
                                                                          5.  (a)  72   (b) 119    (c) 60     (d) 60
                      5.  Prime numbers: 67, 113, 137, 71
                                                                        Progress Worksheet
                         Composite numbers: 123, 125
                     6.  (a)       24         (b)    52                   1.  (a)  the number itself   (b)  1   (c)  even
                                                                            (d) 43     (e) 1
                               6        4          2    26                2.  (a)  True   (b) True   (c) False   (d) False
                                                                          3.  (a), (b) and (d)        4.  9
                            2    3    2    2          2    13             5.  (a)  56 = 2 × 2 × 2 × 7   (b)  72 = 2 × 2 × 2 × 3 × 3
                        (c)        16         (d)       12                   (c)  68 = 2 × 2 × 17   (d)  81 = 3 × 3 × 3 × 3
                                                                             (e)  26 = 2 × 13
                               4        4                                 6.  (a)  28, 56, 84, 112, 140; 28  (b)  18, 36, 54, 72, 90; 18
                                                      4     3
                                                                             (c)  14, 28, 42, 56, 70; 14   (d)  15, 30, 45, 60, 75; 15
                            2    2    2    2
                                                   2     2               7.  (a)   36               (b)    16
                        (e)   45               (f)        36                    2     18                2      8


                            3    15                   4        9                   2      9                2      4
                                                                                       3     3                 2     2
                               3    5              2    2    3    3
                                                                                36 = 2 × 2 × 3 × 3      16 = 2 × 2 × 2 × 2
                            (Answers may vary)
                                                                                        Chapter 8: Frac  ons
                      7.  (a)  63 = 3 × 3 × 7   (b)  108 = 2 × 2 × 3 × 3 × 3
                         (c)  314 = 2 × 157    (d)  96 = 2 × 2 × 2 × 2 × 2 × 3  Exercise 8.1
                         (e)  280 = 2 × 2 × 2 × 5 × 7   (f)  121 = 11 × 11    1.  (a)  F   (b) W  (c)  W   (d) F   (e)  W   (f) F
                      8.  (a)  9, 11, 13, 15, 17   (b)  10, 12, 14, 16, 18    2. (a)  Numerator: 3   (b) Numerator: 4
                         (c)  11, 13, 17, 19, 23   (d)  10, 12, 14, 15, 16         Denominator: 5    Denominator: 7

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