“Read Euler, read Euler, he is the master of us all” written by Robin Wilson or “Euler: the master of us all” written by William Dunham are to show us how great and multifaceted Euler was as a mathematician. Indeed, he was. In this post, I want to write how great he was as an educator. Today was my first session of a course in number theory. I had to start with “sums of two squares“.  Like most other things in introductory number theory, this one also starts with a very simple observation. Some numbers like 5 ( ( 2^2+1^2 […]