Australia

TL;DR because the numbers are a mess and keep changing.

I stopped counting after the M1. I don't even know what the M2 is.

Edit: I looked up the M2 and realised I went there once to do work on the Lane Cove Tunnel.

First time seeing the Ring Roads shield... I can't really think of any ring roads in Sydney but I might be wrong

I find it amusing that he opened with the A28 because that's about the only proper route number I can remember paying attention to - it's useful for running the non-toll route north/south through Sydney. Even then though I would refer to that particular road as the Cumberland highway, the route number is just for keeping track when changing to a differently named road (which you do a few times going through that way).

Generally speaking the only roads I remember by number are a few Sydney motorways that don't have prominent names - what comes to mind is the M5/7/8 and I guess the M4 (though that's partly the F4 in my memory due to spending some early childhood in the Blue Mountains before moving elsewhere).