Hi,

Try this code. To add the code right click on the sheet name and select view code. Paste the code in and then close VB

Private Sub Worksheet_Change(ByVal Target As Excel.Range)
If Not Intersect(Target(1), Range("C26")) Is Nothing Then
    Application.EnableEvents = False
    With Target(1)
         'Assuming your Constant/Multiplier is 15:
        .Value = .Value * 15
    End With
    Application.EnableEvents = True
End If
End Sub
VBA Noob