Select Data/Data Validation and select either whole number or decimal
from the list to restrict the cell to that type of content. You get to
set a min and max and can set up an input message (that appears when
the cell is selected - like a comment that responds to selection not
mouse position) and an error message.

On Jul 21, 1:48*pm, Brazil wrote:
How can I protect a cell so that an alpha character cannot be entered into a
numeric field?