Multiply 0.6 by 4.2.

• A. 2.22
• B. 2.8
• C. 2.52
• D. 3.12

Answer: (C)

When you multiply decimals, first ignore the decimals and multiply the whole numbers, then place the decimal point in the product. Count how many decimal places are in the factors: each factor has one decimal place, so the product should have two decimal places.

Multiply 6 by 42 to get 252, then put the decimal two places from the right: 2.52.

This matches the actual product and also makes sense as a little more than 2.4 (since 0.6 times 4 is 2.4) but not by enough to reach 2.8, so 2.52 is the correct result.