How many times is the value of a bank note printed on its upper face?
Twice in visible numerics, and once in Ultra Violet fluorescent ink.
Banknotes under daylight:-
Banknotes under a U/V light:-
Also…. How can you tell if the notes in question have been used for snorting “nefarious substances”?
Easy, – again they show up under U/V light – organic substances glow or “fluoresce” under U/V :-
Have you ever seen a monster like this? :-
and yes, that IS how wide its stalk was…