Listed numbers are placed in set brackets although this is not essential.

1.
(a) {5, 10, 15, 20} 
(b) {15, 30, 45, 60}  
(c) 15

2.
(a) {1, 2, 3, 4, 6, 8, 12, 24} 
(b) {1, 2, 3, 6, 9, 18} 
(c) 6

3. 
(a) 2 × 2 × 5 or 22 × 5
(b) 2 × 2 × 2 × 3 or 23 × 3
(c) 2 × 2 × 2 × 2 or 24

4.

(a) 4

(b) 1.2

(c) 30

(d) 36

(e) 5.29

(f) 0.16

5. Answers could also be given as fractions.

(a) 0.5

(b) 5

(c) 0.067 (2 s.f.)

(d) 1.25

(e) 0.29 (2 s.f.)

(f) 0.005

 

6. (a) 0.125    (b) 0.4   (c) 0.004

7.

(a) 8.32 × 101

(b) 3.2 × 10 -1

(c) 5.417 × 102

(d) 9.63 × 10 - 3

(e) 8.5 × 100

(f) 3.21 × 104

 

8. (a) 512   (b) 0.00361   (c) 80 000