Decimals × and ÷ whole numbers

This is the procedure for multiplying a decimal by a whole number. Multiply as whole numbers first, then place the decimal point in the product counting from the right by the number of decimal places in the multiplicand.

This is the procedure for dividing a decimal by a whole number in long division. Divide as with whole numbers, and place the decimal point in the quotient directly above the dividend's decimal point.

This formula validates division ($a = b \times q + r$). When dividing $a$ by $b$ to get quotient $q$ and remainder $r$, align the decimal point of remainder $r$ straight down from $a$'s original position.