How can I round significant figures when multiplying?
Do the multiplication and then round to fewest number of significant digits in the factors being multiplied.
significant digits are those that have an experimental value ( have been measured. This is a measure of the precision of the experimental method.
Multiplying two measure values can not increase the precision of the measurements. Therefore after doing the multiplication the digits must be rounded off to the precision of the measurements used in the experiment. The precision is only as good as the weakest of all the measurements. ( The weakest link). Therefore the answer must be rounded off to the number of digits in the least precise measurement.