Multiplication, unlike addition and subtraction, has a simple rule. Figure out the significant digits in each factor. Then choose the smallest one. So if you are multiplying 3.02*4.00001 the 3.02 has 3 digits, the 4.00001 has 6 digits, so the answer will have the smaller number, 3 digits. So the answer is 12.0800302 --> 12.1

Division works the same way.

-Dan