1. Review of yesterday… How many sig figs are in the following? 0.02
0.020
20,020
20,000
2.0x10-3
2,002  1   2     4  1   2     4

2. Intro to Chemistry: Significant Figures! (In calculations)

3. Sig Figs in Calculations
Addition and Subtraction:
LOOK at the decimal places!
The answer is rounded to the same number of decimal places as the number used in the calculation with the least decimal places.
Ex:
–1.345
7.81~ ~
7.8
5.78

4. Multiplication and Division: LOOK at the total number of sig figs
Multiplication and Division: LOOK at the total number of sig figs! The answer is rounded to the same number of sig. figs. as the number used in the calculation with the least significant figures Ex: 17.85/2.13 = ~ x ~
8.38
0.0017