Identify all nonzero digits as significant
Count zeros between nonzero digits as significant
Count leading zeros as not significant
Count trailing zeros as significant only if a decimal point is present
Count trailing zeros in whole numbers as ambiguous unless specified by a decimal point or scientific notation
Use scientific notation to show the intended number of significant figures
In multiplication and division, round to the fewest significant figures among the values used
In addition and subtraction, round to the fewest decimal places among the values used
Keep extra digits during calculations and round only at the end
Round the final result to the correct number of significant figures
Use exact numbers from counting or defined quantities as unlimited significant figures
Apply significant figure rules consistently to measured values