Dan Bricklin, originator of
VisiCalc, explains how it came about
here.
The computer spreadsheet was a great invention but I am not sure it was good for mathematics. (I solved a good few problems by using an incremental approach with a spreadsheet rather work out the appropiate function). Another use of spreadsheets, which I
strongly deprecate, is using it for presenting tables,
Word etc. do that job far better! (If nothing else wordprocessors make one very aware that a page has a finite size, something speadsheets pretend they aren't!