Tree diagrams are used in math to see how many possible outcomes there are. The sample space of a tree diagram shows you how many possible outcomes there are.
Doctors use math daily:- measuring height and weight (percentages, ratios)- measuring blood pressure and heart rate (fractions)- measuring dosages of medications- measuring levels of blood, urine,...
Assuming it is not a variable, e is also known as Euler's Constant.
Wait a minute, Euler's Constant is something different.
e is known as Euler's number (which is about 2.718...) or sometimes...