Rules for Significant Figures

To determine the number of significant figures in a number use the following 3 rules:

- Non-zero digits are always significant
- Any zeros between two significant digits are significant
- A final zero or trailing zeros in the decimal portion ONLY are significant

Example: .5__00__ or .632__000__ the zeros are
significant

.__00__6 or .__000__968 the zeros are NOT
significant

For addition and subtraction use the following rules:

- Count the number of significant figures in the decimal portion ONLY of each number in the problem
- Add or subtract in the normal fashion
- Your
final answer may have no more significant figures
**to the right of the decimal**than the LEAST number of significant figures in any number in the problem.

For multiplication and division use the following rule:

- The
LEAST number of significant figures in any number of the problem
determines the number of significant figures in the answer. (You are now
looking at
**the entire number**, not just the decimal portion)

*This means you have to be able to recognize significant figures in order to use this rule*

Example: 5.26 has 3 significant figures

6.1 has 2 significant figures

**Please also see Appendix A pg 587 of your
textbook**