### 3.5.4 Exact or approximate values

Some number, such as π and √2, can’t be written down
exactly as a decimal number. When computing with such numbers,
Xcas will leave them in exact, symbolic form. If you want,
you can have Xcas automatically give you decimal
approximations for these numbers.

You can set whether or not Xcas will give you exact or
approximate values from the CAS configuration screen. Your choice will
be stored in the variable approx_mode, where a value of 0
means that Xcas should give you exact answers when possible
and a value of 1 means that Xcas should give you decimal
approximations. Your choice will be stored in the configuration file
(see subsection 3.5.10), and so can also be set there.