For HP calc emulators, I have the following:
i41CX+, 42s, i48, and FIN-12C
For other math related stuff I have:
ProStats, Quick Graph, and Math Ref
I also have Documents to Go, which has prett good Excel-compatible spreadsheet along with its other apps. However, to make the best use of Docs to Go, it would be best to have an external keyboard. I'm currently researching external keyboards. Does anyone have a recommendation?
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"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill