What is 0.4 x 8?

What is 0.4 x 8?

• A. 3.0
• B. 3.2
• C. 3.4
• D. 3.6

Answer: (B)

Multiplying a decimal by a whole number uses the decimal’s place value. 0.4 is four tenths. Eight copies of four tenths add up to 32 tenths, which is the same as 3.2. A quick way to see it is to multiply the digits as 4 × 8 = 32, then place the decimal so there is one digit after the decimal (because 0.4 has one decimal place), giving 3.2. The exact product here is 3.2.

Multiplying a decimal by a whole number uses the decimal’s place value. 0.4 is four tenths. Eight copies of four tenths add up to 32 tenths, which is the same as 3.2. A quick way to see it is to multiply the digits as 4 × 8 = 32, then place the decimal so there is one digit after the decimal (because 0.4 has one decimal place), giving 3.2. The exact product here is 3.2.