A spreadsheet a financial program that was created in the 1980s and quickly became a killer app. A spreadsheet is like a calculator on steroids. Not only can it perform basic mathematical computations but, you can create formulas within the spreadsheet and link the numbers together.
The magical part of a spreadsheet is that when you make a change to one number in the spreadsheet, you can see instantly how it affects the other number(s) on the sheet. In a sense, you can simulate the outcome of a math equation, your money, or anything else that deals with numbers before you actually do it in rl. It is an amazing application.
Lotus 1-2-3, Microsost Excel, Visicalc are all spreadsheets with Visicalc being the granddaddy of them all