Restrict user entry to numeric values only

[Guest]

I have Active X control textboxes embeded in a spreadsheet. I created an if
then statement to check if the value is numeric. If the value is numeric
then I use it in a calculation if not the user is prompted by a text box
telling them to only enter numeric values. However, I can not figure out how
to write a condition that "checks" if the value includes alphabetic
characters. This is what I have so far

Dim Prompt As String
If txtQPAuto.Value is <condition??> then
txtQPAuto.Value =
Application.WorksheetFunction.Round(txtQPAuto.Value, 0)
txtTQP.Value = txtQPAuto.Value + txtQPWC.Value + txtQPGL.Value +
txtQPProp.Value + txtQPUmb.Value
Else:
Prompt = MsgBox("Please enter a whole number value.", vbOKOnly,
"Total Quoted Premium")
End If

 

[Guest]

This one is so obvious as to not be obvious.

if isnumeric(txtQPAuto.Value) then

isnumeric returns true or false depending on whether the contents are
numeric or not...