1. How many sig figs are there?
1. The leftmost nonzero digit is the most significant digit
2. If there is no decimal point, the rightmost nonzero digit is the least significant digit
3. If there is a decimal point, the rightmost digit is the least significant digit even if it is a zero.
4. All digits between the least and most are also significant.
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2. Examples
3010 20
20.
20.0
30.010
3.200 x 104
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3, 6, 1, 2, 3, 5, 4

3. Examples 100 1.0 x 102 100. .012 .000150 37 people in a class
50,000 at a rally
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1, 2, 3, 2, 3, n/a, ??

4. How Many Sig Figs?
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5. How many sig figs in
1250 ? W 3

6. How many sig figs in
300 ? W 1

7. How many sig figs in
300. ? W 3

8. How many sig figs in
3.0 x 102 ? W 2

9. How many sig figs in
2.10 ? W 3

10. How many sig figs in ? W 7

11. How many sig figs in
.0232 ? W 3

12. How many sig figs in
.00150 ? W 3

13. How many sig figs in
8.900 x 105 ? W 4

14. Rule for multiplication and division
Round final answer to least number of sig figs of the operands:
123.50
x 21
round to 2 places: 2600
Never round until totally done.
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15. Whiteboards
x and / answer rounding
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16. Express the answer with the correct number of sig figs:
= 33,225 -> 33,000 W
33,225 > 33,000

17. Express the answer with the correct number of sig figs:
/ 323 = ? =
-> .316 W
>.316

18. Express the answer with the correct number of sig figs:
8.015 / 570 = ? =
-> .014 W
> .014

19. Rule for addition and subtraction
Round final answer to least common place:
+21.1
> as an expressed answer
Again, never round until totally done.
<IB apparently does not require this rule>
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20. Whiteboards
+ and - answer rounding
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21. Express the answer with the correct number of sig figs:
= ?
= > 16.2 W
= 16.2

22. Express the answer with the correct number of sig figs:
= ?
= 110 -> 110. W
110 > 110.

23. Express the answer with the correct number of sig figs:
= ?
> 25 W
24.52 > 25

24. Express the answer with the correct number of sig figs:
= ?
= 116
- > 100
Quit your whining - use 116 W
100