This button opens up a small menu, and allows you to choose from over 80 different conversions with two clicks.  

1. Make sure the number you want to convert from is in the calculation window.

2. Click on the Conv button.

3. Select the category.

4. Click on the unit that the number in the calculation window represents (ie. teaspoons, etc.).

5. That's it!  The result with all units in that category is displayed on the tape.