4.50×102mL−(0.0245L) can be written to correct significant figures:

Given:(i) 4.50×102mL (ii) 0.0245L=24510000×1000mL=24.5mL=0.245×102mLSo, we have : 4.50×102mL (two decimal places)−0.245×102mL (three decimal  places)                                         =4.255×102mLSince, the result pertains to least decimal places (=2),4.255×102mL=4.26×102mLSince, the result pertains to least decimal places (=2),4.255×102mL=4.26×102mL