Problem-Solving Strategy

 When you are solving some physical problem, try to write your solution in the form of one symbolic equation, where on the left you have the symbol of an unknown physical parameter that you have to calculate, and on the right, you have symbols of only known physical parameters and known constants. Only after this step should you make substitutions on the right, replacing symbols with physical values. If you are doing multi-step calculations using intermediate calculations, write and use intermediate calculations with as many significant figures as possible.

But enter the final result using the correct number of significant figures after rounding the calculated final value. Rounding off in intermediate calculations often makes the final result incorrect. Before you enter the final result, check again what the units of the final results should be according to the text of the problem. The test system accepts as correct results only numbers obtained in expressions written in these units.