Here is a way to catch most outcomes of interacting with the dialog;
Dim value As String
value = InputBox("Please enter a #", "Determine Limit", 10000)
If (StrPtr(value) = 0) Then
MsgBox "You pressed cancel or [X]"
ElseIf (value = "") Then
MsgBox "You did not enter anything"
ElseIf (Val(value) = 0 And value <> "0") Then
MsgBox "Invalid number"
Else
MsgBox "You entered " & value
End If