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?