Can data be entered in a formula cell and have the formula calculate a result?

I had a coworker ask if he could create a formula cell and be able to enter data in it to get the formulated result. I told him that I was sure it could not be done in the way he wanted. But then I became curious:

1. Can data be entered in a cell with a formula, which then runs through the formula and displays the desired result?
- Ex. Formula is entered in A1, beginning data is entered in A1, formulated result is displayed in A1. (hidden formula, background formula, separate sheet formula)

or

2. Can a formula (entered in a separate cell) read a cell where data is entered and then display the formulated result in the same cell?
- Ex. Formula is entered in A1, beginning data is entered in A2, A1 calculates data from A2 and displays result in A2.


Let me know if I need to try and explain myself better. Any suggestions are appreciated. Thanks.

I just found another thread that referenced question 1 and suggested researching macros. I would still like to know if question 2 is possible. Thanks.