# What is e? (VIDEO!)

There are essentially two ways to construct the number e: one through the study of compound interest and one through the study of basic derivatives in calclulus. (And it is not at all obvious these two numbers that result are the same number e!!)

In this video I describe the calculus approach and briefly show why “e” is the most natural and eeeeasy number to use in calculus. (That it connects to compound interest is for another video.)

Full details of all this work appears in volume 5 of THINKING MATHEMATICS.