Each of formula constituent elements represented in real mathematical notation is written by a user via an input device on a display screen. While confirming positions of graphic elements indicative of each of the respective inputted constituent elements with respect to the display screen, the user forms a desired formula. On the basis of types of the inputted constituent elements and their positions on the display screen, an arithmetic relationship between the formula constituent elements is automatically obtained by a computer. A computer program to solve this formula is automatically produced by the computer based on the resultant arithmetic relationship. The solutions of the formula are displayed on the display screen as numeral values and graphic representations.