Multiply 0.75 by 0.4. What is the product?

Multiply 0.75 by 0.4. What is the product?

• A. 0.04
• B. 0.75
• C. 0.3
• D. 0.12

Answer: (C)

When you multiply decimals, multiply them as if they were whole numbers, then place the decimal point so the total number of digits after the decimal matches the sum of the digits after the decimal in both factors. For 0.75 and 0.4, ignore the decimal points and multiply 75 by 4 to get 300. There are two digits after the decimal in 0.75 and one digit after the decimal in 0.4, so use three digits after the decimal in the product. Put the decimal three places from the right in 300 to get 0.300, which is 0.3. You can also see this with fractions: 0.75 is 3/4 and 0.4 is 2/5, and (3/4)×(2/5) = 6/20 = 3/10 = 0.3.

When you multiply decimals, multiply them as if they were whole numbers, then place the decimal point so the total number of digits after the decimal matches the sum of the digits after the decimal in both factors.

For 0.75 and 0.4, ignore the decimal points and multiply 75 by 4 to get 300. There are two digits after the decimal in 0.75 and one digit after the decimal in 0.4, so use three digits after the decimal in the product. Put the decimal three places from the right in 300 to get 0.300, which is 0.3.

You can also see this with fractions: 0.75 is 3/4 and 0.4 is 2/5, and (3/4)×(2/5) = 6/20 = 3/10 = 0.3.