DUDEK Emil: Typical USA ROCKWELL calculator with sound logic and clear display. Both the silver trim and any lettering on the keyboard surround have a tendency to rub off so finding good examples is not easy. Original case is padded brown plastic with flip top cover and tuck-in tab at the front. Logics: [C] cancels an incorrect numerical entry, pressing a second time [C] clears the calculator. Divide by zero shows ‘0.o’ whilst overflows are shown with the answer and ‘o’ in the far right (ninth) digit. The error is recoverable by use of [C]. Using ‘o’ means you cannot tell if the overflow is positive or negative until [C] is pressed. Minus sign is shown on the far right (ninth) digit. Input overflow is suppressed, typing in nine digits ignores the last one. Memory functions are called up by two button presses; i.e. (M) (+) will add the main register contents to the memory. Memory storage is not flagged, you have to remember it. It has automatic constant on all functions.