TITLE: Scratch Pad software for Windows
QUESTION [5 upvotes]: I'm looking for software that can serve as a replacement for a physical "scratch pad", on a Windows system with only keyboard and touchpad interfaces.  This is intended to facilitate manual calculations, but not actually do any computation.
$\LaTeX$ is good for some things, but I haven't found an easy way to do things like vertical addition/subtraction/multiplication/division with the same speed & comfort as I might do on a scratch pad.
Excel and Notepad can serve the purpose, but they're a bit clumsy at it.  Paint could do, but is not so great to use without a mouse.
Is there any purpose-built "scratch pad" software out there?  Or, are there other workarounds I might not have thought of which work well on a laptop with no regular mouse?

REPLY [2 votes]: You might try Math-o-mir. I haven't used it myself but the site says: 

The idea behind Math-o-mir was: "why can't I use my PC as simple as I am using pencil when writing mathematical equations?"