1. Significant Figures (a.k.a. Sig Figs)

2. Significant Figures In science, measured values are reported in terms of significant figures. Significant figures indicate the precision of the instrument used to make the measurement, i.e. how close the markings are on the instrument.

3. Significant Figures The reported measurement will consist of all digits known with certainty, plus one final digit which is somewhat uncertain or is estimated.

4. Significant Figures

6. Significant Figure Rules 1)Digits other than zero are always significant. 96 g2 sig figs845 g?? 61.4 g3 sig figs72.39 g?? 0.52 g2 sig figs

7. Significant Figure Rules 2) Zeros between non-zero digits are significant. 5.029 mL 4 sig figs1609 m?? 306 g 3 sig figs3.005 L??

8. Significant Figure Rules 3) Final zeros after the decimal are significant (the “after-after” rule). 4.20 m3 sig figs0.500 g?? 5.7200 m 5 sig figs302.0 g?? 82.0 m3 sig figs

9. Significant Figure Rules 4)Zeros used solely for placing the decimal are NOT significant. They are just placeholders. 7000 g 1 sig fig 7 x 10 3 0.00783 kg3 sig figs 7.83 x 10 -3

10. Significant Figure Rules 5) The presence of a decimal after a zero (or zeros) makes that zero significant. 400. m3 sig figs 2580. g4 sig figs

11. Significant Figure Rules 6) A line placed OVER a zero means that the zero is significant. 20003 sig figs 30002 sig figs

12. Atlantic and Pacific Rule If all those rules are a bit too much, try the Atlantic and Pacific Rule.

13. Atlantic and Pacific Rule If a decimal is present in the number, start counting sig figs from the Pacific (from the left). Find the first non-zero digit and count to the end. Example: 0.00103 has 3 sig figs.

14. Atlantic and Pacific Rule If a decimal is absent from the number, start counting sig figs from the Atlantic (from the right). Find the first non-zero digit and count to the end. Example: 744,500 has 4 sig figs.

15. Your turn: How many significant figures? 1)0.025 2) 54000 3) 0.005670 4) 2.40 x 10 4 5) 5007.00

16. Your turn: How many significant figures? 1)0.0252 2) 54000 3) 0.005670 4) 2.40 x 10 4 5) 5007.00

17. Your turn: How many significant figures? 1)0.0252 2) 540002 3) 0.005670 4) 2.40 x 10 4 5) 5007.00

18. Your turn: How many significant figures? 1)0.0252 2) 540002 3) 0.0056704 4) 2.40 x 10 4 5) 5007.00

19. Your turn: How many significant figures? 1)0.0252 2) 540002 3) 0.0056704 4) 2.40 x 10 4 3 5) 5007.00

20. Your turn: How many significant figures? 1)0.0252 2) 540002 3) 0.0056704 4) 2.40 x 10 4 3 5) 5007.006

21. Your turn: How many significant figures? 6) 0.508 7) 0.0058363 8) 0.0600 9) 34000.00 10) 10200

22. Your turn: How many significant figures? 6) 0.5083 7) 0.0058363 8) 0.0600 9) 34000.00 10) 10200

23. Your turn: How many significant figures? 6) 0.5083 7) 0.00583635 8) 0.0600 9) 34000.00 10) 10200

24. Your turn: How many significant figures? 6) 0.5083 7) 0.00583635 8) 0.06003 9) 34000.00 10) 10200

25. Your turn: How many significant figures? 6) 0.5083 7) 0.00583635 8) 0.06003 9) 34000.007 10) 10200

26. Your turn: How many significant figures? 6) 0.5083 7) 0.00583635 8) 0.06003 9) 34000.007 10) 102003

27. Significant Figures: A small distinction Exact numbers: numbers used to count, not measure, are considered to have an infinite number of sig figs. For instance: 365 days in a year, 12 inches in a foot, and 26 letters in the alphabet

28. Significant Figures: the estimated digit Significant figures include the digits known with certainty plus one final estimated digit. The estimated digit is the last significant digit. It may or may not be the last digit in the number.