PURPOSE: To set automatically an initial value to generate easily high-quality random numbers, by providing a random number generation processing program in a calculator and setting the counted vlaue of a counter as the initial value of the random number generation processing when an initial value setting request is issued at the program operation time.

CONSTITUTION: The clock output from a clock oscillator 1 is applied to a counter 2 as a program counter and a counter 3 as a watchdog timer and is counted successively in accordance with respective purposes. Clocks from the oscillator 1 are applied to a counter 4 for the random number processing, and the counted value is taken into this counter 4 by the designation of a random number processing routine F. This routine F is a kind of processing routine in the calculator and is accessed when the random number processing is requested. The counter 4 is used as an interval timer, and the counted value of the counter 4 is set as the initial value when the initial value setting is requested at the program operation time, and the random number generation processing is processed by the successive calculation method due to the mixed congruence method.