1. Significant figures

2. Significant figures: What are they and why do they matter?
Importance: to ensure the accuracy of our measurements
To make sure we tell others only what we actually know based on our equipment and it’s limitations
Significant figures: all the numbers actually measured plus one that is estimated

3. Rules for significant figures
Non zeros are always significant:
has 6 sig figs
Zeros within a number are always significant. Both 4308 and contain four significant figures.
Zeros that do nothing but set the decimal point are not significant.
470,000 has 2 significant figures.
has 2 sig figs
Trailing zeros that aren't needed to hold the decimal point are significant.
4.00 has 3 significant figures.
has 2 significant figures

4. Rules for addition and subtraction of significant figures
The number of decimal places in the answer is equal to the number of decimal places in the quantity with the smallest number of decimal places
  =

5. Rules for multiplication and division of significant figures
The LEAST number of significant figures in any number of the problem determines the number of significant figures in the answer.
2 x 10.0 = 20
66 / 2 = 33 = 30