drag a cell to the right to create a what-if scenario.

The ability to run what-if scenarios in spreadsheets revolutionized business. By creating and changing models as fast as you could think, anyone could test scenarios and use these data to make decisions.

But the 'what-if' interaction in spreadsheets is anemic; you fiddle with a number, see what happens in your model, change the number back. You can't see multiple possibilities at the same time, can't save a scenario and show it to other people. I believe that the power of what-if scenarios lies in comparison, seeing the effects of different changes simultaneously.

In this prototype, dragging right in any cell will create a shadow copy of your spreadsheet that you can change independently of your original copy. You can create several of these and compare scenarios.

—Glen Chiacchieri, December 2014

Steven Levy's 1984 "A Spreadsheet Way of Knowledge":

Yet what really has the spreadsheet users charmed is not the hard and fast figures but the "what if" factor: the ability to create scenarios, explore hypothetical developments, try out different options. The spreadsheet, as one executive put it, allows the user to create and then experiment with "a phantom business within the computer."

"Before the spreadsheet, you barely had enough time to do the totals," said Archie Barrett, a Capitol Hill staff member who uses an IBM PC-XT to work up spreadsheets for the House Armed Services Committee. "Now you put in a number and see whether you're above or below the total. You can play what-if games. What if we don't order as many tanks? What if we order more?"

The what-if factor has changed the way Allen Sneider, a partner in the Boston office of Laventhol & Harwath, a national accounting firm, approaches his job. Sneider bought an Apple in 1978, but he was not able to make it useful in his business until he saw an early copy of VisiCalc and became one of the first professionals to use the program. He explained:

Before, you would suggest a change to a client, get a staff member to calculate it, send it to the typist, to the proofreader, and recalculate it to make sure there weren't any errors. Now you have a machine right there with the client. Want to see what happens with a different return on investment? Sheltering? Interest rates changing by half of a percent? It's done in a minute. Before you'd be tempted to say, "Let's leave it the way it was." The whole mental attitude toward preparing projections has changed.

The what-if factor has not only changed the nature of jobs such as accounting; it has altered once rigid organizational structures. Junior analysts, without benefit of secretaries or support from data processing departments, can work up 50-page reports, complete with graphs and charts, advocating a complicated course of action for a client. And senior executives who take the time to learn how to use spreadsheets are no longer forced to rely on their subordinates for information.