The program automatically extends the fraction bar as far as necessary to encompass the entire fraction. The numerator and denominator are automatically set in a small-size font for an in-line fraction and in a full-size font for displayed fractions. You can set the defaultsCustom_defaults.tex for entering fractions from the Math tab sheetMath_defaults.tex in the User SetupUser_setup.tex dialog box.
You can edit the properties of a fractionEdit_fraction.tex to toggle the fraction line on and off or to set the size of the numerator and denominator.
You can enter fractions in the format x/y by typing a slash to divide the numerator and the denominator, but fractions created with a slash have no automatic formatting features.