An account starts at 24.6 dollars, receives 7.85 dollars, then pays 3.2 dollars. Enter the final amount in dollars.

Explication

Using two decimal places, 24.60 + 7.85 = 32.45 and 32.45 - 3.20 = 29.25, so the final amount is 29.25 dollars. Right-aligning the written digits would mix tenths and hundredths and corrupt both steps.