Abstract: A data processing apparatus includes a novel method of entering the data for a function which requires two integral operands. First and second preselected sets of the digits of the current output numerical value are interpreted as the first and second integral operands. In the preferred embodiment a predetermined number of the least significant whole number digits is interpreted as the first operand and the predetermined number of the most significant fractional digits is the second operand. This data entry method reduces the amount of memory required to store the operands and to execute the function. This data entry method also enables entry and execution of these two variable functions in the same mathematical hierarchy as single operand functions. In the case of the preferred embodiment, in which this data entry method is used for calculating permutations and combinations, this is the preferred and mathematically correct method of executing these functions.