Abstract: An electronic calculator is provided with an input keyboard for receiving numerical data, a storage interconnected to the keyboard for storing the received numerical data, processing circuitry interconnected to the storage for processing the numerical data, a display for displaying steps of the arithmetic process of the numerical data, and a visualizing unit for visualizing the numerical data in response to the display. Each step of the arithmetic process of the data may be indicated in the display in response to instructions provided on the keyboard.

Abstract: An electronic calculator comprises a keyboard for receiving numerical data, storage registers for storing the numerical data, a processor unit for processing the numerical data stored in the storage registers, a display unit for visually displaying the numerical data, a blocking circuit for blocking the visual display of a computed result from the processor unit, and a releasing circuit to discontinue the blocking of the visual display of the result, thereby causing the operator of the calculator to not know the result until receiving instructions.