This program was actually suggested by my AP Statistics teacher since there is no function on the TI-83 to find t-test critical values.  There are several others in my class that did similar programs, but oh well...
To use this program, simply run it and enter in the desired percent (as a decimal) and the number in your sample.  The calc will think for a while and display the upper and lower critical values for that value.
This program stores the lower critical value in variable "A" and the upper in "B"
The results may differ from the table due to the table's rounding error.
If you don't know what a t-test or a critical value is, this program is not for you.