I don't know what IM3 is and maybe neither does the Calculator.
In such cases you get to look up the classic formula and enter it
according to circuit realities.
I recommend that, given the craptastic UX of the Calculator, you
copy/pasteas you go, "waypoints" and an eventual evaluatable
expression into some text editor on the side, and save to file
(because I have not been able to find any facility to save calculator
expressions "locally" in IC6 / ADE Calculator).