1. Measurement: Significant Figures

2. Significant Figures  Significant Figures (sig. figs.): the number of digits that carry meaning contributing to the precision of a measurement or calculated data.

3. Precision and Accuracy Low Accuracy High Precision High Accuracy Low Precision High Accuracy High Precision

4. Significant Figures  Significant figures, which are also called significant digits, are very important in science.  Each recorded measurement has a certain number of significant figures.  Calculations done on these measurements must follow the rules for significant figures.

5. Significant Figures  The significance of a digit has to do with whether it represents a true measurement or not.  Any digit that is actually measured or estimated will be considered significant.  Placeholders, or digits that have not been measured or estimated, are not considered significant.

6. Significant Figures  There are 5 rules to determine which zeros in a number are significant or not.

7. Rules for Significant Figures  Rule #1: All non-zero digits (1-9) are significant. For example: 453 number of sig figs______ 345.21number of sig figs______

8. Rules for Significant Figures  Rule #2: Zeros between non-zero digits are significant. For example: 12.007 number of sig figs______ 3008007 number of sig figs______

9. Rules for Significant Figures  Rule #3: Zeros to the left (“leading” zeros) of the first non-zero digit are NOT significant. For example: 1.02 number of sig figs______ 0.12 number of sig figs______ 0.00127 number of sig figs______ 0.00040301number of sig figs______

10. Rules for Significant Figures  Rule #4: If a number ends in zeros (“lagging” zeros) to the right of the decimal point, those zeros are significant. For example:  2number of sig figs______ 2.0 number of sig figs______ 2.00number of sig figs______ 2.000 number of sig figs______ {This signifies greater precision.}

11. Rules for Significant Figures  Rule #5: If a number ends in zeros (“lagging” zeros), the zeros to the right are NOT significant IF there is NO decimal point present. For example: 47100 number of sig figs______ 20060number of sig figs______ 40000number of sig figs______

12. Sig. Figs. Practice Ex 1) 0.020110 Ex 2)730800 1) 48001 2) 9807000 3) 0.008401 4) 40.500 5) 64000 6) 64000. 7) 64000.00 8) 0.0107050 Ex 1) 0.020110 (5 sig. figs.) Ex 2)730800 (4 sig. figs) 1) 48001 (5 sig. figs.) 2) 9807000 (4 sig. figs.) 3) 0.008401 (4 sig. figs.) 4) 40.500 (5 sig. figs.) 5) 64000 (2 sig. figs.) 6) 64000. (5 sig. figs.) 7) 64000.00 (7 sig. figs.) 8) 0.0107050 (6 sig. figs.)