e and handy rules
The number e pops up all over the math world. It is the base of the natural logarithm, irrational, and transcendental.
I spent a long time not caring much about e, but now I do. You better know as much as you can about e when you are meditating on the Riemann Hypothesis.
e calculated to two decimal places is 2.71. The natural log of 10 is 2.3, of 100 is 4.6, and of 1,000 is 6.9. For each factor of 10 the natural log increases about 2.3. That’s a handy rule to know.
Too bad life, in general, does not have more handy rules like e and it’s natural logarithm.