A spreadsheet is a grid; a presentation needs a few clear messages. Slidy turns rows and columns into the slide types that suit numbers: key figures (three or four big numbers with a short label), comparison tables (this year against last year, plan against actual, product A against product B), timelines for monthly or quarterly series, step-by-step process slides and 2x2 matrices when your data sorts items on two axes.
Every number on the slides comes from your file. When a slide needs a figure your sheet does not contain, Slidy writes "XX" instead of guessing, so you can spot it and fill it in. Slides are written in the language of your document.