Lesson 2

Rounding Off - General Guidelines

When you round off a number, it is generally for one of two reasons: convenience or precision. When you round off for convenience you can do it any way you want to. When you round off for precision you have to look at the precision of the numbers that went into the calculation, and make the precision of the answer match the precision of the least precise measurement.

As in the experiment for determining density, the numbers used in calculations are often from measurements. Measurements by their nature have limited precision. Any numbers obtained from the calculations using measurements will also be limited to the same degree of precision as the measurements that went into the calculation. Roughly speaking, any calculated value is no more precise than the least precise number that goes into the calculation.