I looked thru lots of calculator apps but they seemed to be either tip calculators or scientific ones. I'd like on that's just like the calculator i use at my desk. I know how to figure out what the tip amount would be so don't really want one that does only that. and the one that seems to be in my Droid doesn't have a % key, unless i've missed it. I just don't see the need to have 2 different kinds of calculators taking up space on my phone. any suggestions?