Even if you don't have a meat thermometer, don't go straight to cutting your roast beef in half to figure out whether or not it's done. Instead, use a skewer.
And, on the flip side, absent a proper meat thermometer, you can also swap the tool for a cake tester, a very thin, metal skewer with a heat-resistant end, to check a steak's temperature and ...
The "metal skewer heat" technique is the final, non-thermometer way to tell. Poke a skewer into the thickest part of the meat and leave it there for 5 seconds. Take it out and gently rest it just ...