The elusive negative zero on the HP 30b

[EdS2]

Yes, I too thought the 20b and 30b would behave the same, where they offer the same function. (I suppose we could dig into firmware versions: it's possible this behaviour isn't in all versions.)

Also interesting, I thought, that not all large negative odd numbers do the same... except, the behaviour seems slightly inconsistent. Previously I thought I'd found that -33333 and -11111 did not lead to minus zero - but today they do. Sometimes. It seems to depend a bit on the stack, or perhaps on some other state.

In fact, I think I'd even say the minus sign appears very briefly and is then removed, in cases where positive zero is returned. But that's debatable. (I remember very old calculators would do their trailing zero suppression just slowly enough to leave a visual impression.)