Hexadecimal
  By default, Calculator appears in decimal mode when you
  start the Calculator.
  To change to Hexadecimal mode, choose the Hexadecimal
  menu item from the Mode menu.  The Calculator appears
  Hexadecimal mode.
  Additional topics:
  *   Mode Menu
  *   Edit Menu
  *   File Menu
  *   Overview of Calculator
  *   Hexadecimal Keypad and Special Function
      Bindings