Fractions & Decimals
Introduction to :
Multiplying decimals is only slightly more complicated than adding and subtracting decimals. The good news is that you don't have to worry about lining up the decimals. In fact, you don't even need to think about the decimals until the final step.
How to Multiply Decimals
- Stack the two numbers that you are multiplying as you would any numbers
- Multiply as you usually do
- To place the decimal in your final answer, count how many total numbers are behind (to the right of) the decimals in both of the original numbers
- In your answer, starting from the right, move the decimal that many places to the left
Check out the examples below for these steps in action.
Since there are three numbers behind decimals (2, 5 and 9), we must move the decimal three places to the left in our product. Our final answer is: 1745.625
When multiplying, it is ok to reverse the order of the numbers (not so much with subtraction and division).
Since there are five numbers behind decimals (3, 2, 0, 5, and 8), we must move the decimal five places to the left. Our final answer is: 1.93856.
Since there are six numbers behind decimals (1, 2, 5, 1, 7, and 5), we must move the decimal six places to the left. However, there are not enough digits to do this, so we must add a zero place-holder. Our final answer is: 0.021875.