$ Proportioned Paper From a Square
Here's a method for getting dollar bill proportioned paper from a square that I developed myself. It's more accurate than the two common methods that you find in books and online (one results in a 7:3 rectangle and the other in a 1+√2:1 rectangle). While the 7:3 method is nearly as accurate as my method, it's far more difficult. My method is as simple as the 1+√2:1 method but much more accurate.