Another +1 for the DM42 here. It's a great calculator and very nicely built. It uses a transflexive memory LCD display, kind of similar to eink, which is a pre

Another +1 for the DM42 here. It's a great calculator and very nicely built. It uses a transflexive memory LCD display, kind of similar to eink, which is a pretty good match to the application, batteries last forever, and the software is very good. It compares very favorably to the HP-35s (and the WP34s) I was using prior to it.