Grid Capture or other Object

Dear recipient,

I need a display with 5 fields of capture in field 2 the user must simply define a formula (not the operation). What object should I use for this? further questions to capture the character that defines the formula how to guarantee that
are inserted correctly to the database and makes no strange characters?
Thanks for your help, regards.

Unfortunately your issue is not clear.
Could you clarify your issue. Some screenshots are appreciated.