Compute 0.5 × 0.4.

• A. 0.04
• B. 2
• C. 0.2
• D. 4

Answer: (C)

When multiplying decimals, multiply as if there were no decimals, then place the decimal point so that the product has the total number of decimal places equal to the sum of decimal places in the factors. Here, each factor has one decimal place, so the product should have two decimal places. Multiply 5 by 4 to get 20, then place the decimal two places from the right: 0.20, which is 0.2. The result is 0.2.