1. Significant Figures All the digits that can be known precisely in a measurement, plus a last estimated digit.

3. 1. Every non-zero digit is assumed to be significant. 24.7 m = 3 significant digits 0.8234 = 4 significant digits

4. 2. Zeros between non-zero digits are significant. 7003 m = 4 significant digits 1.503005 cm = 7 significant digits

5. 3. Zeros left of nonzero digits are not significant. 0.0071 m = 2 significant digits 0.00000000998 cm = 3 significant digits

6. 4. Zeros at the end of a number, to the right of a decimal point are always significant. 43.00 m = 4 significant digits 3.00100 cm = 6 significant digits

7. 5. Zeros at the rightmost end of a measurement that lie to the left of an assumed decimal point are not significant. They are place holders. 300 m = 1 significant digit 7000 cm = 1 significant digit

8. 6. Two situations have an unlimited number of significant digits. Ex. 1: Counting – if you count 25 people in your room, there is exactly that number of people. Ex. 2: Defined quantities – 60 min = 1 hour or 100 cm = 1m. These are defined numbers.

9. How many significant figures in each? 5.432 g ________ 40.319 g _______ 146 cm ________ 3.285 cm ________ 0.189 kg _________ 429.3 g _________ 2873.0 km _________ 99.9 mL _________ 0.000235 g ________ 144 lbs ________

10. Rounding To round you need to figure out how many significant figures the number should have – If the number after the last significant digit is less than 5, it is dropped – If the number is greater than 5, the last significant digit is raised by one. “Naked 5 Rule” – Only use when number to be rounded is followed by a ‘5’ & nothing else – If number before ‘5’ is odd, round it up – If number before ‘5’ is even, leave it

11. Round to 2 significant figures 1.7.334 m 2.42.1 m 3.42.6 m 4.0.125889 g 5.0.004553 g 6.122 g 7.128 mL 8.464 mL 9.0.0000667 mL 10. 99.99 km

12. Addition and Subtraction Round to the same number of decimal places as the measurement with the least number of decimal places.

13. Addition 6.789 789.98 + 54.1 850.869 850.9

14. Subtraction 453.9 - 5.6687 448.2313 448.2

15. Multiplication and Division Round the answer to the least number of significant digits present in the problem.

16. Multiplication 5.678 x 45.1 = 256.0778 256

17. Division 89.2 / 5.5 = 16.2181818181818 16

18. Complete the calculations 1.12 cm + 0.031 cm + 7.969 cm = ________________ 2.0.085 cm + 0.062 cm + 0.14 cm = _______________ 3.3.419 g + 3.912 g + 7.0518 g + 0.00013 g = _____________ 4.30.5 g + 16.82 g + 41.07 g + 85.219 g = _______________ 5.143.0 cm + 289.25 cm = _______________________ 6.41.025 cm – 23.28 cm = _____________________ 7.289 g – 43.7 g = _______________________ 8.2.89 cm x 4.01 cm = ____________________ 9.17.3 cm x 6.2 cm = _____________________ 10.3.08 m x 1.2 m = ____________________ 11.5.00 mm x 7.3216 mm = __________________ 12.20.8 dm x 123.1 dm = ____________________ 13. 8.071 cm2 / 4.216 cm = ___________________ 14. 109.3758 m2/ 5.813 m = __________________