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Cabrillo College

Pre-Algebra: Lesson 060

Lesson Description

Students learn to multiply a decimal by a whole number in the same way that one would multiply a whole number by a whole number (vertically). However, at the end of the problem, students must determine where the decimal goes in the answer by counting the total number of digits to the right of the decimal point in the original numbers, then placing the decimal point in the answer so that the answer has this same total number of digits to the right of the decimal point. For example, after multiplying 5.42 x 8, since there are a total of 2 digits to the right of the decimal point in the original numbers, place the decimal point in the answer so that there are 2 digits to the right of the decimal point.