When using a spreadsheet package to answer "what if" questions, the user must change:?

When using a spreadsheet package to answer "what if" questions, the user must change a selected variable to see the outcome of the change.

Today due to the advanced technology and rising demand of computer technology we find different and many types of spreadsheet software packages, to write a few:

MS Excel

Google Sheets

Numbers

Easyoffice

Smartsheet