Counting Significant Figures

Indicate the Number of Significant Figures for each of the following:

Rules for Zeros

Rule
Examples
Zeros appearing between nonzero digits are significant• 40.7 L has three sig figs

• 87009 km has five sig figs

Zeros appearing in front of nonzero digits are not significant• 0.095 987 m has five sig figs

• 0.009 has one sig fig

Zeros at the end of a number and to the right of a decimal are significant• 85.00 g has four sig figs

• 9.000 000 000 mm has 10 sig figs

Zeros at the end of a number but to the left of a decimal may or may not be significant. If such a zero has been measured, or is the first estimated digit, it is significant. On the other hand, if the zero has not been measured or estimated but is just a placeholder, it is not significant. A decimal placed after the zeros indicates that they are significant.• 2000 m may contain from one to four sig figs, depending on how many zeros are placeholders. For measurements given in this text, assume that 2000 has one sig fig.

• 2000. m contains four sig figs indicated by the presence of the decimal point.

Scientific notation - All digits expressed before the exponential term are signicant.• 5.060 x 10-3 m has four sig figs.