## 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. |

300 000 000 m/s

1 200 000 g

19 cm^{3}

0.0040 kg

8.030 x 10^{-2} L

9.98000 g

107 010 mm

0.00090 cm

7.1000 kg

4.00 x 10^{3} m

2.37 x 10^{-2} m

2.030 x 10^{5} nm

4.3020 x 10^{-8} m

0.0025 mL

5 000 m

19.3 s

2.05 x 10^{7}g

6.04 km

1.050 s

3 005 m

10 450 m

0.012 055 000 km

56.05 cm

5050 mL

0.05150 km