org-table-formula-field-format

org-table-formula-field-format is a variable defined in `org-table.el'.
Its value is

"%s"

Documentation:
Format for fields which contain the result of a formula.
For example, using "~%s~" will display the result within tilde
characters. Beware that modifying the display can prevent the
field from being used in another formula.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.1 of Emacs.