Chapter 1 - Measurement and Problem Solving - Learning Path Questions and Exercises - Exercises - Page 30: 51

$a). 14.7$ $b). 11.4$ $c). 0.20 m^{2}$ $d). 0.82$

When added or subtracted, the decimal places of the result must have least decimal place of the 2 quantities. So, a). 12.634 + 2.1 = 14.7, b). 13.5 - 2.134 = 11.4 When multiplied or divided, the number of significant figures must be with the least number of significant figures among the quantities. so, c). $\frac{22}{7} \times (0.25m)^{2} = 0.20 m^{2}$ d). $\sqrt \frac{2.37}{3.5}=0.82$