Singapore Primary Mathematics U.S. Edition Answer Keys 4A-6B
(first printing only)

This page last updated February 22, 2005

 

         
  p. 1 Rounding Off Numbers (pp. 14-17)  
    8. 1200  
       
  p. 16 2 Multiplication (pp. 45-51)  
    15. 23.70  
    16. 80.20  
    17. 18.20  
         
  p. 17 Review B (p. 65)  
    5.(a) 30; 29.4  
    5.(b) 63; 62.3  
    5.(c) 20; 19.95  
    5.(d) 33; 32.97  
         
  p. 18 Review C (p. 80)  
    11.(b) 24, or 48, or 72...  
         
  p. 18 Review D (p. 83)  
    11. 9 in.  
    15. 10:05 p.m.  
         
  p. 19 1 Identifying Solid Figures (pp. 86-89)  
    7. 2  
    8. 2  
         
  p. 22 Review 2  
    13. $35  
    14. answers mislabeled as 13 in key  
         
  p. 26 Review 7  
    8. 3/8  
    11. 400 ml  
         
  p. 33 missing right column:  
   

Practice 5B (p. 82)
1. 5 : 12
2. 12 : 4 : 7
3. 4 cups
4. 77
5. 5 : 6
6. (a) 30 cm (b) 20 cm
7. (a) 4 m3 (b) 8 m3
--------------
8. 102 kg
9. $75

Unit 6 - Angles

1 Measuring Angles (pp. 83-84)
1. 123º
2. 240º
3. 325º
2. (a) 135º (b) 45º
3. (a) north-east (b) north-west

2 Finding Unknown Angles (pp. 85-88)
146; 34; 146
85; 45; 180
150; 150; 360
1. (a) 48 (b) 143 (c) 345
2. x = 134º; y = 46º; z = 134°
3. angle COB = 155°
4. angle DBE = 90°
5. angle x = 35°
6. angle m = angle n = 40°
7. angle a = 29° angle b = 145° angle c = 85°

Review B (pp. 89-92)
1. 19,000
2. $43,000
3. (a) 6700 (b) 72,800 (c) 350,000 (d) 430 (e) 580 (f) 628
4. 24
5. 4/15
6. 1/4
7. 2 h 15 min
8. 60 cm
9. (a) $105 (b) $80 (c) $165
10. 3 m
11. 1/10 m
12. 48
13. 1 1/5 kg
14. 375
15. $504
16. $195
17. $45
18. $57
19. $36
20. 300 m2 70 m
21. $120
22. 14 cm
23. (a) 44 m 84 m2 (b) 58 cm 140 cm2
24. (a) angle a = 160° (b) angle b = 205°
25. (a) angle x = 207° (b) angle x = 47°
26. (a) 75 cm2 (b) 42 cm2 (c) 18 cm2
27. 54 m2
28. (a) 24 cm2 (b) 25 cm2 (c) 240 cm2 (d) 10 cm2

  
       
  p. 38 Exercise 25  
    1(a) first fraction should be 5/3  
       
  p. 43 Practice 3A  
    8 160  
       
  p. 50 Review 3  
    18.(a) 30 in.2  
    21. $40  
       
  p. 54 Practice 4C (p. 60) (missing answers to this practice)  
    1. 32%  
    2. 25%  
    3.(a) 150% (b) 50%  
    4. 26%  
    5. 25%  
    6. 20%  
    7. 25%  
    8. 15%  
    9. 40%  
    10. 40%  
         
  p. 55 1 Speed and Average Speed (pp. 74-80)  
    8. 3 1/2  
         
  p. 62 Practice 1B (p. 15)  
    5.(a) 6  
       
  p. 67 Review G (pp. 111-116)  
    1.(b) 2,012,00      
       
  p. 68 Review H (pp. 117-120)  
    4.(a) 1/24