1. Significant Digits Scientific Notation Dimensional Analysis

2. Counting numbers have an infinite number of significant digits because they’re derived from… counting. (You can’t have two and a half cars.) Measured numbers are precise to a point and the last digit is an estimate. How tall are you? 79” vs. 79.25” 2 m = 201 cm 201 cm or 201.3 cm

3. Going to the moon. Have Direct TV Going to mars?

4. Number 25 0.25 301 3.01 40 400 40.00 0.040 2 2 3 3 1 1 4 2 # of Sig Figs

5. Number 25 0.25 301 3.01 40 400 40.00 0.040 2 2 3 3 1 1 4 2 # of Sig Figs

6. 1) All nonzero numbers are always significant. (25) 2) Any zero between two significant digits is also significant. (301) 3) Leading zeroes are never significant. (0.01) 4) Final zeroes (ending zeroes) are only significant if they follow (to the right of) the decimal. (300, 3.0, 3.00) 337.2 1004 0.00300

7. Multiplication and Division are not the same as those for Addition and Subtraction.

8. Your answer can be no larger than the number with the fewest significant digits. 27.2 x 3 = 81.6 or 82 or 80? (3 s.d. or 2 s.d. or 1 s.d.) 8.92/3.2 = 2.7875 2.8

9. Answer can be no more precise than the least precise number. 6.26 + 3.1 = ? 9.36? 9.4 27 + 1.9752 = 29

10. Useful when numbers are very large or very small (678,000,000,000,000,000,000,000,000) Also useful to express a number in significant digits. (5,000 to two sig figs.) All numbers can only be expressed as the product of a number between 1 & 9 inclusively and a whole-number power of ten. So 5,000 would be 5.0 x 10 3. 678,000,000,000,000,000,000,000,000 = 6.78 x 10 26

11. 2323 x 3434 = 6 12 1212 = 2323 x 3434

12. 2323 x 3434 = 6 12 1212 = 1313 x 3232

13. 2323 x 3434 = 6 12 1212 = 1313 x 3232

14. 2323 x 3434 = 6 12 1212 = 1111 x 1212 = 1212

15. This concept also works with units. Since there are twelve inches in one foot then… 6.5 feet = ? inches

16. Conversion factor This concept also works with units. Since there are twelve inches in one foot then… 6.5 feet = 78 inchesx 12 inches 1 foot

17. How far is it to the sun? Need to know the speed of light is 186,000 miles/second Light takes 8 mins to get to earth from the sun. Work it out! 8 mins 60 s min x 186,000 mi s x =

18. How far is it to the sun? Need to know the speed of light is 186,000 miles/second Light takes 8 mins to get to earth from the sun. Work it out! 8 mins 60 s min 186,000 mi s x x =90,000,000 mi

19. 9 x 10 7 mi