Ok, I apologize for not being clear.

In A1 I want to put one of the following three strings of text:
"Inventory", "Inventory - % of COGS", "Inventory - DIO". Cell B1 has to
be formatted as an integer number if "Inventory" is chosen, a
percentage number if "Inventory - % of COGS" is chosen or as a special
format Xd (where d stands for days) when the third condition is
selected.

Thank you again.