Illustration: The mass of a box is 2.3 kg. Two marbles of masses 2.15 g and 12.39 g are added to it. Find the total mass of the box to the correct number of significant figures.
2.3 kg
Total mass = 2.3 + 0.00215 + 0.01239 = 2.31 kg
Total mass in appropriate significant figures be 2.3 kg
(While addition you retain the number of digits after decimal places as they are in the observation with the minimum number of decimal places)