How Many Humans Would a T-Rex Need to Eat Every Day to Survive?

If Jurassic Park taught us anything, it's that humans are easy prey for T-Rex. But just how many human beings would such a dino need to chow down on every day just to survive?

Some math by Randall Munroe reveals that it's not as many as you might think. Tyrannosaurus rex weighed about as much as an elephant, and best estimates suggest it needed to consume around 40,000 calories per day. Given that an 80-kg human contains about 110,000 calories of energy, T-Rex would probably need to eat about half of an adult—or one ten-year old child!—every day. Or about 80 McDonald's hamburgers. Which really isn't as much as you may've expected! [What If?]