Microsoft Math
Microsoft has had a good but generally unknown history of producing really quite remarkable Mathematics additions to its OS’s and Applications
Microsoft has just published a new version 4.0 get it here
Math contains
- Graphing calculator 
- allows 2D and 3D colour graphing. 
- Formulas and Equations Library 
- more than 100 commonly used equations and formulae. 
- Triangle Solver 
- teaching tool for triangles and their parts. 
- Unit Conversion tool 
- convert units of measure, including length, area, volume, weight, temperature, pressure, energy, power, velocity, and time. 
- The Step-by-Step Equation Solver 
- helps learning on how to solve math problems. 
The Main Site is here
Microsoft Mathematics Add-In for Word and OneNote get it here
I would definitely give it a spin
b.
