To multiply decimals, add up the number of decimal places, remove the decimal points and multiply the numbers. After calculating, place the decimal into the answer using the original number of added decimal places.
- Determine the combined number of decimal places
Add the number of decimal places there are in each number. Do this by counting the amount of numbers after the decimal places in both of the numbers being multiplied. In the example of .25 x .5, .25 has two decimal places because there are two numbers after the decimal point, and .5 has one decimal place because there is only one number after the decimal point.
- Remove the decimal points, and multiply the numbers
Remove the decimal points from each number, creating two whole numbers. Multiply the two numbers. For example, .25 x .5 becomes 25 x 5. The answer to 25 x 5 is 125.
- Place the decimal point in the answer
Use the total number of decimal places in the original numbers to determine where to place the final decimal point. For example, .25 x .5 has three decimal places. Once the whole numbers are multiplied to reach 125, the final answer in this example is .125.