1. Significant Figures Part 1: Counting Sig figs

2. Decimal--Left 0.004703 has 4 significant digits.
 If a number has a decimal, count all digits starting with the first non-zero digit on the left.
Examples:
has 4 significant digits.
18.00 also has 4 significant digits.

3. No decimal--right
If there is no decimal , count all digits starting with the first non-zero digit on the right.
Examples:
140,000 has 2 significant digits.
20060 has 4 significant digits.

4. In both cases, start counting with the first non-zero digit.
00.015
15000

5. Another way of thinking…
These number are always significant:
All NON-ZERO numbers (1-9)
Trapped zeros (6007)
Trailing zeros when there is a decimal (26.00)

6. Complete Sig Fig Self Test
Now Try it on your paper
a) 3.57 m _________
b) g _________
c) m3 _________
d) kg _________
e) mL _________
f) 30 atoms _________
g) g/mL _________
h) s _________
i) 810 oC _________
j) mol _________
k) km _________
l) cm3 _________
Complete Sig Fig Self Test

7. Significant Figures Part 2: math with Sig figs

8. This leads to 2 rules: add/subtract & multiply/divide
Math with sig figs
Calculations shouldn't have more precision than the least precise measurement.
This leads to 2 rules: add/subtract & multiply/divide

9. Addition and Subtraction
The answer should not have more decimal places than the number with the least decimal places.
Example: = =

10. Addition Practice
A) = B) = C) = D) = E) 87.9 – 20 = F) – 119 =

11. Top half of practice sheet (Addition and Subtraction sets only)
Assignment
Top half of practice sheet (Addition and Subtraction sets only)

12. 2. For Multiplication and Division
The answer should not have more significant figures than the number with the least amount of significant figures.
Example: 502 x 3.6 =
1800

13. Multiplication Practice
A) x 402 = B) x 75.2 = C) / 45 = D) 5300 / 456 = E) 4590 / 1234 = F) 141 x =