AUTO displays answers in a similar format as the input. For example, if a fraction is entered in an expression, the answer will be in fraction form, if possible. If a decimal appears in the expression, the output will be a decimal number.
DEC displays answers as integers or decimal numbers.
Note: The ANSWERS mode setting also affects how values in sequences, lists, and tables are displayed. You can also convert values from decimal to fraction or fraction to decimal using FRAC, DEC, and F D located in the FRAC shortcut menu or the MATH submenu.