An apparatus capable of obtaining a result which is desired by an operator, canceling a result when an erroneous operation is performed and facilitating creation of a mathematical expression is provided. This apparatus comprises an indicating mechanism for outputting a position in a mathematical expression and a part in a mathematical expression in accordance with an operation of the operator; an operating mechanism for generating a plurality of proposed transformation results of the mathematical expressions based on the position and the part outputted from the indicating mechanism, and a selecting mechanism for selecting one from a plurality of the proposed transformation results in accordance with an operation of the operator.