[Ideas] Math Multi-Tool

I'm making a math multi-tool and I need some ideas, like equations and stuff like that. I have areas, volumes, and a basic calculator on it and it seems like it needs more. Any ideas would be helpful. I'm mainly doing to get used to VS 2010.

Factorization

This.

How about something that is more 'equation' based. I honestly don't know how I would put that into code.

f(a+h) - f(a)
___________ > You just gotta enter f, meaning you can enter a function for f.
h

Then people should be able to choose how many numbers should be displayed for a and in which step each...in a listbox..

Like it'd say...

f(x) = x²

A | Result

1 result here
2 etc
3 etc

> 1er steps

This would prolly look like this...

((F(A+h)-F(a))/h

You won't get me =/

nevermind <.<