1. Rule for Using Sig Figs in Math: The result of your calculations can never be more precise than your LEAST precise number!

2. Example  You may know very precisely that the volume of your bucket is 401234.2 ml, but if you have a very uncertain number of drops/ml (24 drops/ml)… 24 drops/ml x 401234.2 ml = 24 drops/ml x 401234.2 ml = 9629620.8 drops? 9629620.8 drops?-or- 9600000 drops? 9600000 drops?

3. Multiplication/Division  Round to the same number of places as the number with the least sig figs.  12 x 230.1 = 2761.2 (calculator) = 2800  0.00325 /.120 = 0.0270833333333 (calc) = 0.0271 = 0.0271  = 70.65 (calc) = 70.65 (calc) = 70 = 70

4. Addition and Subtraction  Round to the last sig fig in the most uncertain number. 9.12 + 4.3 + 6.01 = ? 19.43 (calc) 9.12 + 4.3 + 6.01 = ? 19.43 (calc) 9.12 9.12 4.3 4.3 + 6.01 + 6.01 19.4 19.4

5.  0.11001 - 2.12 - 12 = ? -14.00999 (calc) 0.11001 0.11001 2.12 2.12 -12______ -12______ -14 -14

6. Try these on your own…

7. 3.414 s + 10.02 s + 58.325 s + 0.00098 s

8. = 71.76 s

9. 1884 kg + 0.94 kg + 1.0 kg + 9.778 kg = 1896 kg

10. 2104.1 m – 463.09 m = 1641.0 m

11. 2.326 hrs – 0.10408 hrs = 2.222 hrs

12. 10.19 m x 0.013 m = 0.13 m 2

13. 140.01 cm x 26.042 cm x 0.0159 cm = 58.0 cm

14. 80.23 m ÷ 2.4 s = 33 m/s

15. 4.301 kg ÷ 1.9 cm 3 = 2.3 kg/cm 3

16. What if Multiplication/Division and Addition/Subtraction are combined? Do it in steps, according to the order of operations…

17. (2.39 m – 0.2 m) 12.43 s = 2.2 m 12.43 s 12.43 s = 0.18 m/s

18. 2.00 m – 0.500(0 + 3.0 m/s)(3 s) = 2.00 m – 0.500(3.0 m/s)(3s) = 2.00 m – 0.500(3.0 m/s)(3s) = 2.00 m – 5 m = 2.00 m – 5 m = -3 m = -3 m

19. 0.37 m – 1.22 m – (4 m/s)(3.0020 s) 0.5000 x (1.0021s) 2 = 0.37m – 1.22m – 10m 0.5000 x (1.0021s) 2 0.5000 x (1.0021s) 2 = _____- 10 m______ 0.5000 x (1.0021s) 2 0.5000 x (1.0021s) 2 = - 20 m/s 2