Pretty much anything that you used to do on paper with a columnar notebook or worksheet and a calculator, or anything that could be represented in tabular form could probably be implemented in VisiCalc, Lotus 123, and others. Spreadsheets are probably the most successful software application that was ever invented. Certainly one of the most.
After paying by writing out a check, I helped load everything into his car and he drove off into the sunset --- I was then allowed to choose a reformatted disk from the box as a reward and chose _The Softporn Adventure_ (which I then stupidly removed the label from, but it wasn't something I wanted to explain to my parents...).
Back then it was common for people to buy a whole system for their requirements. Hardware and software.
* Person who deals with numbers all day goes to a computer store to browse.
* He sees VisiCalc, and immediately understands what it can do. It *blows his mind*.
* He wants to buy it right away. Pays for $2000 Apple II computer with disk drives to run $100 software; price is no object.
* Shows friends and colleagues.
* They rush to computer store. Repeat.