Significant Figures Rules

From the point of view of significant figures which of the following statements are correct?
(i) 10.5 cm + 8.0 cm = 18.2 cm
(ii) 2.53 m – 1.2 m = 1.33 m
(iii) 4.2 m × 1.4 m = 5.88 m²
(iv) 3.6 m / 1.75 s = 2.1 m s⁻¹