The product 0.5 × 0.2 equals?

• A. 0.2
• B. 0.25
• C. 0.05
• D. 0.1

Answer: (D)

When you multiply decimals, multiply the numbers as if they were integers and then place the decimal point so that the total number of digits to the right of the decimal matches the sum of the decimal places in the factors. Here, 0.5 has one decimal place and 0.2 has one decimal place, so the product should have two decimal places.

Multiply 5 by 2 to get 10, then place the decimal two places from the right: 10 becomes 0.10, which is 0.1.

So the product is 0.1. The other options correspond to different multiplications (for example, 0.5 × 0.5 = 0.25, 0.5 × 0.1 = 0.05, etc.), which aren’t this case.