Transcript Rules for significant figures


Importance: to ensure the accuracy of our
measurements
 To make sure we tell others only what we actually
know based on our equipment and it’s limitations

Significant figures: all the numbers actually
measured plus one that is estimated

Non zeros are always significant:
 1.23456 has 6 sig figs
Zeros within a number are always significant. Both
4308 and 40.05 contain four significant figures.
 Zeros that do nothing but set the decimal point are
not significant.

 470,000 has 2 significant figures.
 0.00000000098 has 2 sig figs

Trailing zeros that aren't needed to hold the decimal
point are significant.
 4.00 has 3 significant figures.
 0.0000050 has 2 significant figures

The number of decimal places in the answer
is equal to the number of decimal places in
the quantity with the smallest number of
decimal places
 1.23 +4.567=5.80

The LEAST number of significant figures in
any number of the problem determines the
number of significant figures in the answer.
 2 x 10.0 = 20
 66 / 2 = 33 = 30