Everything You Need to Ace Chemistry in One Big Fat Notebook by Jennifer Swanson

For example, did the results come from a scale that was
not calibrated to zero?
Was the investigation conducted on a windy day, which
may have interfered with the reading of the lever on
the scale?
Might moisture have affected the mass reading of
a sample that was assumed to be dry?
Did the coarseness of the filter paper used in a funnel
allow fine particles to pass through unaccounted for?
Just because it is impossible to be completely accurate and
precise doesn’t mean that you shouldn’t make your best
effort to be as accurate and precise as possible.
Significant Figures
Sometimes it is impossible to get an exact measurement,
especially if you don’t have sensitive tools. Perhaps
your equipment only produces measurements in whole
numbers and, for example, can’t go to one-tenth (0.1) or
one-hundredth (0.01). The precision of a measurement is
determined by the number of digits reported. The more
precise the measurement tool, the more precise and accurate
the measurements will be. For example, 2.75 cm is a more
accurate reading than 2.7 cm.
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