Taken from http://ualr.edu/rebelford/chem1300/chem1300.htm  Pencasts by Dr. Rebelford
These are experimental pencasts using a livescribe pulse pen. This material is under development and I am not happy with the way they are currently posted. Be sure to turn your speakers on.
Note: Click on the to open the mathcast and to close it.

Arithmetic with Scientific Notation and SI Prefixes:
Addition and Subtraction of numbers in Scientific Notation 

Multiplication and Division of numbers in Scientific Notation 

Converting SI prefixes for numbers in scientific notation 
Percentage Calculations:
Calculating Mass % from the Mass of Two Species 

Calculating Mass from Mass % and the Mass of Other Species 
Calculations Involving Conversion Factors or Temperature Conversions:
Volume from length measurements 

Mass from Volume and Density 

Fahrenheit from Celsius Measurements 

Celsius from Fahrenheit Measurements 