Calculation rules of decimal addition and subtraction;
1) To calculate decimal addition and subtraction, you must first align the decimal points of each number (that is, align the numbers on the same digit).
2) Then calculate according to the law of integer addition and subtraction, and finally align the decimal point on the horizontal line in the obtained number. (There is a 0 at the end of the decimal part of the number, so it is generally necessary to remove the 0. )