OrderNumber

Public Sub DecCheck(Target As String, ByRef KeyStroke As _
Integer)
If InStr(Target, ".") And KeyStroke = 46 Then
KeyStroke = 0
End If
End Sub

Public Sub NumCheck(ByRef KeyStroke As Integer)
If (KeyStroke < 48 Or KeyStroke > 57) And (KeyStroke _
<> 46 And KeyStroke <> 8) Then
KeyStroke = 0
End If
End Sub

Then invoke the code from your TextBox's KeyPress event:
Private Sub txtUnitPrice_KeyPress(KeyAscii As Integer)
DecCheck txtUnitPrice, KeyAscii
NumCheck KeyAscii
End Sub

'One caveat: This code doesn't prevent text characters from being pasted

'in via the clipboard.