The good ol’ days: Numeracy is a fundamental skill for thriving in an information society. But only a few years ago, tables of figures belonged to accountants and mainframes, not bake sales and community theatres. The personal computer spreadsheet changed all that, giving us a fundamental tool for working with numbers. Dan Bricklin built Visicalc, the killer app for the personal computer. In doing so, he changed forever how the world works with numbers.