KingG,
This is kinda klunky but works fine for positive numbers or 0.

Sub InputNums()
Dim NumErr As Boolean, myInp As String, j As Integer
NumErr = True
While NumErr
myInp = InputBox("Enter number", "Input", myInp)
If myInp = "" Then Exit Sub
NumErr = False
For j = 1 To Len(myInp)
If Mid(myInp, j, 1) < "0" Or Mid(myInp, j, 1) > "9" Then
NumErr = True
MsgBox "Enter numbers only"
Exit For
End If
Next j
Wend
End Sub