The Calculator is one of the major characters from The Brave Little Toaster Goes to Mars.
He is a calculator who lives with Toaster and the other appliances belonging to Rob (the Master). He spends most of his time living in the junk drawer with the Hearing Aid, and is often taken out every April 14th to assist Rob with his taxes.
When the Master's son Robbie (the Little Master) gets abducted, the Calculator manages to use the Hearing Aid's readout info to determine where the Little Master had been sent. The Calculator then assists Toaster and his companions on their mission to travel to Mars and rescue Robbie.
The Calculator navigates Toaster and the gang to Mars with the use of heavy duty coordinates downloaded through Compy and into him by Wittgenstein.