The 48 was quite a bit bigger than the 42s, which I think is the main downside. A bit of googling suggests the 48 contains similar features to the 42s, and pro

The 48 was quite a bit bigger than the 42s, which I think is the main downside. A bit of googling suggests the 48 contains similar features to the 42s, and probably more. It can also show the full 4 level stack - the 42s showed 2. However, you're looking for the best all-round scientific calculator (form factor restricted!) the 42s probably wins. The voyager series (including the 15 and 16) were well-made and in landscape format, which is nice for using on-the-go with both thumbs. They are more simplistic though - you see one line of the stack, and there aren't menus - hence several variations to cater for different markets. The HP41 was an impressive programmable calculator for its time, and seems to be more expandable than the 42s. However, the 42s is programmable, has a few more features and a more modern display. Not sure about the WP34, though if you look at the cost of a second hand 42s, you'll see that many people rate it much higher than more modern HP calculators. I think what puts me off more recent calculators and even some other HPs, is the ambivalence about RPN. I really like RPN, and don't like when the UI is compromised to please both. [1] http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv005.cgi?read=9278 http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv005.cg...