Significant digits (also called significant figures and abbreviated sig figs or sig digs) is a method of expressing errors in measurements. All digits that occupy places for which actual measurement was made are reffered to as significant digits. Also all digits used to show a number in scientific notation will be significant digits. The following rules are used to determine the number of significant digits in a measurement:

1. Digits other than zero are always significant.
   
   • 96 g - 2 significant digits
   
   
   • 61.4 g - 3 significant digits
   
   
   • 0.52 g - 2 significant digit
   
   
2. One or more final zeros used after the decimal point are always significant.
   
   • 4.72 km - 3 significant digits
   
   
   • 4.7200 - 5 significant digits
   
   
   • 82.0 m - 3 significant digits
   
   
3. Zeros between two other significant digits are always significant digits.
   
   • 5.029 - 4 significant digits
   
   
   • 306 km - 3 significant digits
   
   
4. Zeros used solely for spacing the decimal point are not significant digits. The zeros are placeholders only.
   
   • 7000 g - 1 significant digit
   
   
   • 0.00783 - 3 significant digits