A sample initially has a mass of 1.05 grams and loses 0.2 grams. Enter its remaining mass in grams.

توضیح

Pad 0.2 as 0.20 and subtract aligned places: 1.05 - 0.20 = 0.85, so 0.85 grams remains. Treating 2 tenths as 2 hundredths would give 1.03 and subtract from the wrong place.