(The word "road" is used here to avoid the route/highway argument.)
Knowing the logic behind road numbers can help you navigate when you are lost.
Roads that circumscribe major metropolitan areas have three digits. Thus, 495 circumscribes the Boston area.
Further, three-digit interstates with a even first digit are ring roads that run around cities, like 495. Odd first digits (like 395 in CT) signify a spur highway to a city.
Roads that run north/south have odd numbers. Thus, 95 runs from Florida to Canada.
Roads that run east/west have even numbers. Thus, Route 2 runs from Cambridge, out through Williamstown, and beyond. I-40 runs from Wilmington, NC, to somewhere way out west, past Texas. And Highway/Route 66 is perhaps the most famous example of an American east/west road.
It also helps to know that the numbers mostly increase from west to east and south to north (for interstate highways at least).
Knowing this logic can (sort of) help you navigate when you are lost.