Abstract: An electronic calculator having a first input mode for inputting one or more algebraic equations, a display for displaying the variable terms of the input equations, and an indicator for selectively indicating any one of the variables being displayed. A second input mode is provided for inputting numeric data in a direct one-to-one relationship with the displayed variables, the input numeric data being simultaneously displayed with their corresponding variables. A calculator operation is performed by the device upon instruction by an operator whereby the input numeric data is substituted for the respective input variables for a selected equation. The display will show the result of the calculation in a position of the display corresponding to the position where an output variable term is displayed. Accordingly, a numerical calculation may be performed by selecting a stored equation and directly inputting numeric data in a one-to-one correspondence with variables in the displayed selected equation.