BYJU's

Byju is envied for his business acumen. He has made it big. He is young. But very enterprising.
This guy is a genius and brilliant and his courses can help you get into IIMs for sure.
Here is the link to his site. Byjus

Constants

Many constants and irrational numbers are nature driven. They exist in nature. Root 2, Root 3, e, Pi, Phi and Gamma. And of course Feigenbaum Constants. Then there is Kinchin constant as well. These are all naturally existing constants. And maybe more.
These constants are beneficial to humankind as they promote healthy life.
Then there are constants like Ramanujan-Landau constant which are deduced constants. Genius mindsets see patterns and deduce interpretations.
Then there are material constants like Avagadro number, Planc's constant etc.
Then of course there are principles like Pareto Principle which is 80:20. These are the most beautiful and practical of all the above.