How many times have you said to yourself, "I hate significant figures!" Although many chemistry students would agree that significant figures are the bane of their existence, we'll be using sig figs throughout the year. Learn the rules well and use them consistently!
Refer back to this page if you need clarification or additional examples for the significant figure rules.
Rule 1. All nonzero digits are significant.
Rule 2. "Captive" zeros are always significant.
Rule 3. "Leading" zeros are never significant.
Rule 4. "Trailing" zeros are not significant UNLESS there is a decimal point in the number.
Rule 5. Digits written out in scientific notation are significant.
Rule 6. All measured values are significant. To indicate precision, measured values should be recorded one decimal place beyond the smallest division marked on the measuring tool.
When adding and subtracting with significant figures, the answer should be rounded so that it has no more decimal places than the value with fewest decimal places.
When multiplying and dividing with significant figures, the answer should be rounded so that it has no more significant figures than the value with the fewest significant figures.