1.

(a) 4.47 (b) 4.5
(c) 0.015 (d) 920
(e) 5 (f) 0.73
(g) 4.245 (h) 90 000
(i) 56 (j) 190

2.
(a) 48 000 people  
(b) 12 kg  
(c) $32 400  
(d)100 runs  

3.

 

Calculation

(a) Estimate

(b) Accurate answer

(rounded, if necessary, to 4 sig. fig.)

9.47 + 4.7

9 + 5 = 14

14.17

34.5 × 2.9

30 × 3 = 90

100.1

(9.42) 2

92 = 81

88.74

8.364.21

8/4 = 2

1.986

4.99 − (5.74 + 3.2)

5 − (6 + 3) = -4

-3.95

4.

(a) 4.8
(b) 4.50
(c) 0.10
(d) 7.294
(d) 427.3
(f) 50

5.

Purchase

Estimated cost

Accurate cost

4 cakes at $4.99 each

4 × 5 = $20

$19.96

2 buns at 99c each

2 × 1 = $2

$1.98

7 biscuits at 22 cents each

7 × 20 = $1.40

$1.54

2 cans of drink at $1.84 each

2 × 2 = $4

$3.68

4 loaves at $2.24 each

4 × 2 = $8

$8.96

Totals

$35.40

$36.12