TI-92 Help -- Exact vs. Approximate Calculations

The TI-92 can do calculations in one of two different modes -- exact and approximate. The screen on the right illustrates the difference. The first calculation is exact -- 1 divided by 9 is exactly 1/9; the second calculation is approximate -- 1 divided by 9 is (rounded off to six digits) approximately .111111.
The MODE screen allows you to choose which of these modes is used routinely. The screen on the right shows Page 2 of the MODE screen. To get to this screen press MODE and then F2. This screen allows you to set three different ways in which calculations will be routinely made. AUTO mode -- This is the usual mode. If possible the TI-92 will make exact calculations but when it is not possible to get an exact answer the TI-92 will display an approximate answer. EXACT mode -- The TI-92 will always display an exact answer. If an exact answer is not possible it will just return the original command. APPROXIMATE mode -- The TI-92 will always display an approximate answer. You select which of these three modes will be used by using the cursor pad to highlight the desired mode and then pressing ENTER twice. In AUTO or EXACT mode you can obtain an approximate answer at any time by pressing green-diamond ENTER.
The pair of screens on the right illustrate the difference between these modes. The particular integral shown cannot be done exactly -- only numerical approximation is possible. The first screen shows the result in EXACT mode -- because an exact answer is not possible the TI-92 returns the original command. If you press green-diamond ENTER or if the calculator is placed in AUTO or APPROXIMATE mode then you will see a result like the second screen.
As usual, the number of digits displayed depends on the Display Digits setting in the MODE screen.