I’ve come across a few posts about an ‘issue’ where the A/P mach number does not match the flying mach number. and have even experienced it myself. This of course has to do with rounding…which brings me to this idea…why doesn’t our HUD display mach to a accuracy of 3 digits? For instance, instead of mach displaying as “0.84” , it could show “0.838”
I think this is how real aircraft display it. In fact, some infinite flight aircraft already use three digits (the embraer jets)