Respuesta :
The rule that applies in this evaluation is that in addition or subtraction operations, the answer (total/difference) should not be more accurate than the least accurate term. In this case, the number with least sig fig is 2.70 or 4.21. The answer here is 9.66 x10-3.
The answer is 2 for the first one and its 9.66x10^-3g for the second one.