B.

To multiply decimals, first multiply as if there is no decimal. Next, count the number of digits after the decimal in each factor. Finally, put the same number of digits behind the decimal in the product.

4.22

× 0.6

2532

How many digits are after the decimals in each factor? (4.22) & (0.6)

There are three digits after each decimals.

2532

| | |

Count from right to left and you will have your answer.

2.532