Page 184 - Math Skill - 4

182 Maths

18. TTh Th H T O 19. 3680 20. 109 21. 17,100 22. 5,000 23. ` 13,000 24. 19,440 minutes 25. 9,89,901
5 1 1 0 6
– 3 4 4 1 7
1 6 6 8 9
Chapter 4: Factors and Multiples
Boot-up :
1. 1 × 12 = 12 2. 12 × 1 = 12 3. 6 × 2 = 12 4. 2 × 6 = 12 5. 3 × 4 = 12 6. 4 × 3 = 12

Exercise 4.1
1. (a) factors (b) 1 (c) itself (d) 0 2. (a) Yes (b) Yes (c) No (d) No
3. (a) Factors of 10 : 1, 2, 5, 10 (b) Factors of 18 : 1, 2, 3, 6, 9, 18 (c) Factors of 63 : 1, 3, 7, 9, 21, 63
(d) Factors of 92 : 1, 2, 4, 23, 46, 92 (e) Factors of 56 : 1, 2, 4, 7, 8, 14, 28, 56
4. (a) 2, 3, 6 (multiple answer) (b) 2, 4, 17 (multiple answers) (c) 2, 4, 5 (d) 2, 3, 4
5. (a) 1, 2, 4 and 8 (b) 1, 2, 3 and 6 (c) 1, 2, 3, 4, 6 and 12 (d) 1, 5 and 25 (e) 1, 3, 5 and 15
(f) 1, 2, 3, 6, 9 and 18 (g) 1, 2, 4 and 8 (h) 1 and 5
6. Yes 7. (a) 18 (b) 3 (c) 4
Exercise 4.2

1. (a) 8 and 3 (b) 7 (c) number itself (d) itself or 1 (e) unlimited
2. (a) Yes (b) Yes (c) No (d) No (e) Yes (f) Yes
3. (a) 28 (b) 6 (c) 56 (d) 156 (e) 18 (f) 24 (g) 132 (h) 90
4. (a) 6, 12, 18 (b) 8, 16, 24 (c) 20, 40, 60 (d) 21, 42, 63 (e) 24, 48, 72
(f) 35, 70, 105 5. 24, 30, 36, 42, 48 6. 17, 34, 51, 68 7. 19, 38, 57, 76, 95 8. (a) 10 (b) 30 (c) 24
Exercise 4.3
1. 3, 5, 7, 9, 11, 13, 15, 17, 19 2. 23, 29, 31, 37
3. 21, 22, 24, 25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49 4. 2
5. (a) Even numbers : 24, 62, 90 Odd numbers : 13, 43 (b) Even numbers : 104, 648 Odd numbers : 53, 237, 913
6. (a) 3, 17 (b) 23, 41 (c) 29, 67, 11 7. (a) 6, 16, 51 (b) 33 (c) 4, 27, 39
8. (a) 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31 (b) 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24 (c) 0 and 1
9. (a) 24 (b) 36 (c) 72 (d) 45 (e) 90

3 8 2 18 2 36 3 15 2 45

2 4 2 9 2 18 3 5 3 15
2 2 3 3 2 9 45 = 3 × 3 × 5 3 5

24 = 2 × 2 × 2 × 3 36 = 2 × 2 × 3 × 3 3 3 90 = 2 × 3 × 3 × 5
72 = 2 × 2 × 2 × 3 × 3
Exercise 4.4
1. (a) Yes (b) No (c) Yes 2. (a) Yes (b) Yes (c) No 3. (a) No (b) Yes (c) Yes
4. (a) No (b) Yes (c) Yes 5. (a) No (b) Yes (c) Yes
Assessment Time
A. 1. (b) 2. (c) 3. (b) 4. (c) 5. (a) 6. (b) B. 1. 60 2. 2 3. 6 4. 6, 4
5. number itself C. 1. (i) 2. (ii) 3. (i) 4. (i)
Chapter 5: Fractions
1 3 1 2
Boot-up : , , ,
4 4 2 8
Exercise 5.1
6 7 1 3 3 5
1. (a) (b) (c) 2. (a) (b) (c) 3. (a) (b) (c)
8 12 6 7 11 9
4. (a) two-sevenths (b) seven-sixteenths (c) nine-nineteenths (d) three-tenths