The default calculator on the Droid X is buggy! Two calculations that I confirmed are buggy are simple ones but wrong nonetheless:
233.6 - 229.8 = 3.799999999 = on the Droid X Calculator (3.8 in real life)
215.2 - 209.8 = 5.399999999 = on the Droid X Calculator (5.4 in real life).
I downloaded a free calculator app that appears to be bug free, but wanted to let y'all know that the default one has problems with simple math!
FYI ... My daughter has the same new Droid X phone. I called her at college and she did the calculations and they came out wrong on her phone as well. Goofy!