I'm trying to find a pot value that will null my op amp's input offset (8mV typical).

First, I shorted Vinp and Vinn together and calculated effective Zin value that will give me Vout=0 which resulted negative value for Zin (-352.5Ohms)

Negative Zin value makes me to think this is not the right way to find the pot value. Is this the right way to do it?

How can I find a pot value that will null the offset?

Thanks!