How to Multiply Decimals
When multiplying decimals, the key is to keep track of the number of decimal places. Learn how with this guide.
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You Will Need
- Decimal numbers
- Whole numbers
- Calculator
- Decimal places
Steps
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Step 1
Multiply whole numbers
Multiply the 2 numbers containing decimals the same way you would if they were whole numbers containing no decimals.
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For example, to multiply 0.5 and 2.2, first obtain the product of 5 times 22, which is 110.
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Step 2
Count decimal places
Count how many digits follow the decimal points in the two decimal numbers you are multiplying.
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In the case of 0.5 and 2.2, there are a total of two digits following the decimal points.
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Step 3
Correctly position the decimal point
Position the decimal point in the answer, also known as the product. The product will have as many decimal places as the sum of the decimal places in the two original numbers, also called the multiples. First, add up the number of decimal places in the two multiples.
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For instance, there is one decimal place in 0.5, and one decimal place 2.2. 1 plus 1 equals 2, so the answer should have two decimal places.
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Step 4
Shift decimal point
Starting at the right of the product, shift the decimal point to the left the same number of places as the sum of the decimal places in your product.
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The product, 110, becomes 1.10.
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Step 5
Eliminate zeros
Eliminate any zeros at the end of the product -- 0.5 times 2.2 equals 1.1.
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The word decimal comes from the Latin word for 10th part.
