You many want to study how to make educated guesses. This are sometimes called back of the napkin calculations or Fermi estimation problems. There is one cours

You many want to study how to make educated guesses. This are sometimes called back of the napkin calculations or Fermi estimation problems. There is one course on MIT Opencourseware that teaches it: https://ocw.mit.edu/courses/18-098-street-fighting-mathematics-january-iap-2008/ https://ocw.mit.edu/courses/18-098-street-fighting-mathemati... The book used in the course is also very good. The author is the same as the course instructor Prof Sanjoy Mahajan.