The TI-89 will convert from one unit to another. This is a very useful menu. There are also many built-in constants available via a menu, or they can be typed in directly. There is a list of predefined constants and units on pages 77 - 79 of the TI-89 manual. You can also create your own user-defined units. This capability will be used in courses other than mathematics and an extensive study of this topic is beyond the scope of this tutorial. However, you can find directions below for converting from one unit to another.
Example: Convert 120 miles per hour to kilometers per hour.
Enter 120_mph _ kph . The units are accessed via the units menu by pressing . Scroll down to the velocity menu.