ti-89 question: auto, exact, approx?

[Nocturnal]

what in the world are these options?

 

[mchammer187]

exact will always try to express your answer in terms of a fraction or square root

approx will always give u a decimal answer

i am guessing auto is like a combination of both

i use auto and exact and if i need to approx i just multiply the answer by 1.0

like 3/4

auto = 3/4
exact = 3/4
approx = .75

1/3

auto 1/3
exact 1/3
approx .3333333333333333333333333333

 

[Prodigy^]

best setting is probably to have it on auto, and when you want an excact value, press the green button (diamond) and enter, that'll give you approx. or you can type '.' after a number somewhere in your equation