I want to show a Drop Down List in a cell in Google Sheets, where user can choose a list of words. But I want to let to user to input any number too. Since the only way I know to show off a drop down list is by setting a data validation, if user inputs something different from the given list it will display an error message (actually it should not be an error on how I pretend it to). I know (and I have already done it) I can use a formula to achieve this behavior, but it does not show off the requiered Drop Down List.
Create a drop down using data validation and include a circular reference to the cell your drop down list is located. Then you will never receive an error for typing something not on the list since what you typed is also included in the list.
Create validation with A:A and put in A1 a reference to your drop down list and put the rest of your list in A2 and below.