50g

Hello dr, Using complex with your HP 50g  is really easy, First thing you want to know is to toggle from real to complex, for this just press and hold [left-shift] and then press [TOOL], on top of the screen toggles from C to R (leave it in C). For example, let's say you want to calculate the parallel combination of Z1= 120 + j95 and Z2 = 150 – j80, that is: Zp = (Z1*Z2)/(Z1 + Z2).
Make sure you are working with soft menus. (flag -117 must be set).
Let's work with just four decimal places:
Press and hold [left-shift] and then press [MODE] press [F1] to choose FMT then press 4 and [F2] to choose FIX.
In the math menu let's choose complex
Press [left-shift] [SYMB] then [NXT]  and [F3] to choose CMPLX.
Let's enter the first impedance:
120 [SPC] 95 [F4] (R->C combine two real numbers in a complex number)
Let's enter the second impedance:
150 [SPC] 80 [+/-] [F4]
Find the product
[*] (this means the product key)
Let's retrieve the two impedance values:
Press [left-shift] [ENTER] (ANS in RPN retrieve the last argument(s))
find the sum
[+]
finally divide the two values
[/]
And there you have it, the value of Zp.