A whole number is added to a number with two digits after the decimal point. To make sure the answer is reasonable, how many digits should the sum have after the decimal point?
To make sure the answer is reasonable, the number of digits after the decimal point in the sum should be the same as the number of digits after the decimal point in the original number. In this case, the original number has two digits after the decimal point, so the sum should also have two digits after the decimal point. Therefore, the correct answer is 2.
