Significant Figures

Significant figures are the digits in any measurement that are known with certainty plus one digit that is uncertain.

Number of significant figures = All certain digits + One uncertain digit

Determine the number of significant figures in each of the following measurements:

1. 14.386Rule #1 All non-zero digits are significant.

5 sig. fig.

2. 0.0078

Rule #4 Trailing zeros at the end of a number are significant only if the number (a) contains a decimal point or (b) contains an overbar.

Rule #2 Zeros to the left of the first non-zero digit are not significant.

Rule #3 Zeros between non-zero digits are significant.

3. 5.0078

4. 65.00

2 sig. fig.

5 sig. fig.

4 sig. fig.

1. 36 000Rule #4 Trailing zeros at the end of a number are significant only if the number (a) contains a decimal point or (b) contains an overbar.

5 sig. fig.

2. 7 800

Rule #3 Zeros between non-zero digits are significant.

Rule #4 Trailing zeros at the end of a number are significant only if the number (a) contains a decimal point or (b) contains an overbar.

Rule #2 Zeros to the left of the first non-zero digit are not significant.

3. 0.00069

4. 30008

2 sig. fig.

2 sig. fig.

5 sig. fig.

More Practice Problems

Determine the number of significant figures in each of the following measurements:

a) 5 000Rule #4 Trailing zeros at the end of a number are significant only if the number (a) contains a decimal point or (b) contains an overbar.

1 sig. fig.

b) 3005

Rule #2 Zeros to the left of the first non-zero digit are not significant.

Rule #1 All non-zero digits are significant.

Rule #2 Zeros to the left of the first non-zero digit are not significant.

c) 0.000002

d) 0.00050

4 sig. fig.

1 sig. fig.

2 sig. fig.

e) 7 698Rule #1 All non-zero digits are significant.

4 sig. fig.

f) 76 980

Rule #2 Zeros to the left of the first non-zero digit are not significant.

Rule #4 Trailing zeros at the end of a number are significant only if the number (a) contains a decimal point or (b) contains an overbar.

Rule #2 Zeros to the left of the first non-zero digit are not significant.Rule #4

g) 0.50

h) 70

4 sig. fig.

2 sig. fig.

2 sig. fig.