Who built the world's first electronic calculator using telephone relays, light bulbs and batteries?

George Stibitz made the original version of this in 1936 on his kitchen table, hence the name “Model K”. Using scrapped relays from Bell Labs and strips of metal from a tin can, it can add two binary digits. In November 1937, George Stibitz, then working at Bell Labs (1930 - 1941), completed a relay-based calculator he later dubbed the “Model K” (for “kitchen table”, on which he had assembled it), which calculated using binary addition.