Using Significant Figures in Calculations
When doing math with measurements, you need to follow specific rules for significant figures to maintain proper precision. These rules differ depending on the operation you're performing.
For addition and subtraction, your answer should have the same number of decimal places as the measurement with the fewest decimal places. For example, when adding 34.234 + 22.4, the answer must be rounded to 56.6 (one decimal place) because 22.4 only has one decimal place.
For multiplication and division, your answer should have the same number of significant figures as the measurement with the fewest sig figs. If you multiply 3.01 × 2.0, your answer should be 6.0 (two sig figs) because 2.0 has only two significant figures.
Remember: In science, reporting a measurement with too many significant figures is just as incorrect as reporting too few - it misrepresents the precision of your data!
Rounding numbers correctly is an essential skill. To round 3.515014 to 5 sig figs, you get 3.5150. When rounding to fewer sig figs, like rounding 3.52 to 1 sig fig, you get 4 because the "5" causes you to round up. For large numbers like 136,758 rounded to 4 sig figs, you get 136,800 or 1.368×10⁵ in scientific notation.