1. An electronic calculator comprising: input means having a plurality of control elements including ten manual control keys representing numerical values from 0 through 9; input register means for accumulating a numerical argument entered by at least one of said control elements; unary function means for generating the unary function of the numerical argument in said input register means, the unary function generated by said unary function means being usable as a factor in a succeeding calculation; a single manual control button for initiating operation of said unary function means; and output means for displaying the unary function generated by said unary function means in decimal digit form.