org-table-formula-use-constants

org-table-formula-use-constants is a variable defined in `org-table.el'.
Its value is

t

Documentation:
Non-nil means interpret constants in formulas in tables.
A constant looks like `$c' or `$Grav' and will be replaced before evaluation
by the value given in `org-table-formula-constants', or by a value obtained
from the `constants.el' package.

You can customize this variable.