18. A calculation device comprising: a plurality of entry keys configured to allow a user to enter mathematical expressions, the plurality of entry keys including a fraction entry key to allow a user to enter a fraction having a numerator and a denominator; a display configured to display the mathematical expressions and an editing cursor; a hardware processor, wherein the hardware processor: enables entry and editing of mathematical expressions by the user, determines, when the fraction entry key is pressed, whether to place a position of the editing cursor into the numerator or denominator of the fraction, wherein said determination is based at least in part on one or both of a prior mathematical expression entry and a position of the editing cursor, and configures the display to output the fraction with the editing cursor in the position thus determined.
18. A calculation device comprising: a plurality of entry keys configured to allow a user to enter mathematical expressions, the plurality of entry keys including a fraction entry key to allow a user to enter a fraction having a numerator and a denominator; a display configured to display the mathematical expressions and an editing cursor; a hardware processor, wherein the hardware processor: enables entry and editing of mathematical expressions by the user, determines, when the fraction entry key is pressed, whether to place a position of the editing cursor into the numerator or denominator of the fraction, wherein said determination is based at least in part on one or both of a prior mathematical expression entry and a position of the editing cursor, and configures the display to output the fraction with the editing cursor in the position thus determined. 19. The calculation device of claim 18 , where when the fraction entry key is pressed and the hardware processor determines to place the position of the editing cursor into the denominator of the fraction, all or part of a previously entered expression is placed into the numerator of the fraction.