1. 1-2 Significant Figures: Rules and Calculations (Section 2.5, p. 23-28)

2. Rules for Sig Figs in Numbers: Nonzero digits are ALWAYS significant: 97.3 m has 3 sig figs “Leading” zeroes are NEVER significant:0.02 km has 1 sig fig These zeroes simply act as placeholders “Captive” zeroes are ALWAYS significant: 304 sec has 3 sig figs “Trailing” zeroes with a decimal (anywhere) are significant: 4.100 m has 4 sig figs “Trailing” zeroes without a decimal are NOT significant: 700 m has 1 sig fig “Exact” or counting numbers have no sig figs: 3 pens has no sig figs

3. Practice for you 100 m = ____ sig figs vs.100. m = ____ sig figs 0.003 L = ____ sig figs303.0 cm = ____ sig figs 0.0010100 = ____ sig figs 13 14 5

4. Rules for Significant Figures in Calculations: Addition and Subtraction: Add or subtract all numbers; the answer has as many decimal places as the least accurate number. Example: 677 9.2 + 6.33 722.53 but since the first number is only reported to the 1’s place, the answer with sig figs would be 723

5. Multiplication and Division Multiply and divide all the numbers and report the answer with as many sig figs as the number with the fewest sig figs. Example: 22.1 x 9.234 = 204.7but since 22.1 has three sig figs, the answer should be reported as 204

6. Misc Sig Fig Rules: For scientific notation, look to the # before the x10: 3.01 x 10 2 has 3 sig figs Round 5’s up. Besides using a. to indicate significance, an underline can also be used: 300. m = 3 sig figs = 300 m Numbers in conversions are “exact”, with no sig figs:1 kg = 1000 g The 1000 has no sig figs associated with it. 10. cm = 0.10 m = 0.0010 kmNote how all have 2 sig figs

7. To practice sig figs and get immediate feedback on accuracy, go to: http://science.widener.edu/svb/tutorial/index. html http://science.widener.edu/svb/tutorial/index. html