50g

I couldn't figure out how to change from the drop down menus to the soft menus.

Here's the procedure I figured out:
Convert from rectangular to polar or viceversa:
1. White Mode button
2. Arrow down to Coordinate System.
3. Select the soft key; Choose
4. Change the mode to the one your converting too.
5. Place your entry in (X,Y) format using parenthesis.  Thats left arrow and second set of parenthesis down.  Use right arrow and comma, to put in a comma between.
6. Press enter.
7. Note: When entering polar form you have to put the angle symbol after you put in the comma.  That's ALPHA, right arrow, 6.