Ok, I'm from europe, so I never had to deal with inches and feet. I also have all my calculators in engineering mode, because I have often very large and very small numbers (electronic). But that also depends on for what you use your calculator. I have an HP50g but the units menu is something I tryed in the beginning and think at least for me is not useful. And yes, an HP50g would be more like an TI-89.