So obviously it was mentioned in a song
How do you figure that, Dr. Cox? All I know is that if you asked the question Angela had in mind (which might not have been “is it mentioned in a song?”), she’d give it a yes answer.
Q2: If you search for it in the JoCopedia search box, does a relevant result appear?
(ETA: Lex, I think the Doctor meant 13+13+13+14 = 53.)