[1] http://sonorouschocolate.com/notes/index.php?title=The_best_...
Certainly using the exact list is a step beyond that; but you can in fact get very accurate at guessing which words might be on it without memorizing the list
[0] 4*5 assuming that 1 letter is one bit of entropy, which is a rule of thumb when you're compressing gigabytes of text to log2(26^(4*5)) if we just count the combinations of letters