Texas Instruments TI-89 Titanium User Manual page 159

— All numeric results, where possible, are displayed in floating-point
APPROXIMATE
(decimal) form.
Results are rounded to the precision of your graphing calculator and displayed
Note:
according to current mode settings.
Because undefined variables cannot be evaluated, they are treated algebraically.
For example, if the variable r is undefined, pr
— Uses the EXACT form where possible, but uses the APPROXIMATE form when
AUTO
your entry contains a decimal point. Also, certain functions may display APPROXIMATE
results even if your entry does not contain a decimal point.
Operating the Calculator
Fractional results are evaluated
numerically.
Symbolic forms, where possible, are
evaluated numerically
A decimal in the entry forces a
floating-point result.
2 2
= 3.14159⋅r .
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