sig figs

all nonzero digits

significant

interior zeros , eg 80098

significant

trailing zeros that fall after a decimal point, eg. 43.00

significant

trailing zeros before a decimal point, eg. 3200.98

significant

leading zeros, eg. 0.000453

NOT significant

zeros to the right of all nonzero digits, eg. 4000

uncertain. if no further info is given, those zeros are not significant, so only 1 sig fic

exact numbers

have an unlimited number of significant figures, come from counting individual objects, integral #’s that r part of an equation, defined quantities 

multiplication & division w/ sig figs

the result has the same number of sig figs as the measurement w/ the fewest number of sig figs

addition & subtraction w/ sig figs

the result has the same number of decimal places as the measurement w/ the fewest number of decimal places

Calculations Involving Both Multiplication/Division and Addition/Subtraction

follow standard order of operations (PEMDAS) , determine correct number of sig fig in the intermediate answer WITHOUT ROUNDING, then do the remaining steps, round at the end