Debating a flat earther is usually a waste of time. They’re not seeking resolution and they’ve always got “well that’s just part of the conspiracy” to fall back on.
I’m not sure if it’s possible to say “oh well 1x4 = 4 is just part of the conspiracy.”
Though I guess there’s also the even more frustrating endeavour of arguing semantics. I’m right because I’ve redefined how these operators work. And I’ll hand wave a reason for why my redefinition is more correct.