Despite the 50g being a direct follow-on to the 48 series by way of the 49s, it starts in algebraic textbook-entry mode, not classic RPL like the 48GX. Worse, it requires two separate settings to make it behave like its ancestor:

• Mode → Operating Mode → RPN
• Mode → Disp → Stack → Uncheck Textbook

Now it operates like a 48-series unit!¹

Well, mostly. The 50g still has the CAS feature lacking in the 48 series, so pressing ENTER doesn’t get you the numeric answer you may be expecting; it gets you another copy of the expression! You have to press →NUM instead to convert it from symbolic form to numeric, where it will give answers like 9.E0 when you know for a fact it should be 8.999953 or whatever. This is a result of another strange design decision: when you switch it from the default Standard display mode to Scientific, the precision defaults to 0! You must raise this to something more useful to get answers better approximating the true internal result.

1. ^{^} Or, indeed, like a HP-28S. Lovely design!