(This is an example of a short title opening up to show the full question.)
What is the biggest whole number the TI-89 can handle?
The TI-89 can produce a whole number answer with as many as 630 digits. Try 4^40 in EXACT mode.
1208925819614629174706176 But you can calculate 4^1000 and higher, if you have the patience to scroll through all the digits.