HP-15C CE woes: 1 bug, 2 limitations, 3 questions

[Voldemar]

[DEC] on screen 0 d
111 on screen 105 d
[ENTER]
[HEX] on screen 6F h
Aha, there is F as last digit, must add 6×16^0, we know
0
[f] FLOAT 0 on screen 105.
6
+
on screen 111.
[BSP]
[DEC]
239 on screen 137 d
[ENTER]
[HEX] on screen EF h
(must add 6×16^0 and 6×16^1)
0
[f] FLOAT 0 on screen 137.
102
+
on screen 239

This way for now