I was taught the importance of this in my first year of Physics undergrad. Fermi approximations (or order of magnitude estimation), from Fermi problems (https:/

I was taught the importance of this in my first year of Physics undergrad. Fermi approximations (or order of magnitude estimation), from Fermi problems (https://en.wikipedia.org/wiki/Fermi_problem https://en.wikipedia.org/wiki/Fermi_problem). It is a highly valuable skill in STEM fields in my opinion. Sometimes knowing a rough number can tell you what to expect, and can immediately indicate whether something is wrong (or could go wrong).