Calculators Ti-89 titanium convert numbers to fractions

[apples]

is there any quick way to convert numbers to fractions then back to decimals, without changing the mode.

also if i type in log 54, it gives me log 54.
i don't get an answer
even if i put in
ln 32
it gives me ln 32, not an answer.

i've learned to input functional equations and make graphs etc..
but can't really do a lot what i could do with my previous scientific calculator quickly.
help is appreciated.

 

[deiki]

Press the key just below "2ND" ( the green one ), then "ENTER"

 

[z-component]

On page 2 of the mode dialog box there is a mode called Exact/approx. If this is set to auto, you will get exact answers (as rational numbers) whenever possible. To get approximate answers (as decimals) you can press the diamond key, the "key just below 2nd," before entering to give an approximate answer. When you enter ln 32 you get ln 32 as an output because this is the exact answer. If you are looking for the decimal approximation, you need to use diamond. Note that if you set the mode to approx., you will always get decimal answers, which tends to be annoying. I recommend leaving it on auto for this reason.

 

[apples]

thanks a lot

 

[Mech_Engineer]

Another way to get an approximate answer is to add a decimal place!

In Auto mode:
ln(32) gives you 5 ln(2)
but ln(32.) gives you 3.46574

Same applies for log(54)

log(54) returns ln(54)/ln(10)
but log(54.) returns 1.73239

 

[z-component]

Good point, Mech_Engineer. However, many times I use numbers from previous calculations, so I would have to arrow over to the end of the value to place the decimal point, which is cumbersome. I find that the diamond key is faster.