Without knowing information such as the series (date) and condition, the best guess is that it's worth $2.
It is not worth anything
Nothing.
$1.00
Assuming the 666 is part of the eight-digit serial number, it's worth one dollar.
10 dollars
Nothing as of yet!
twenty dollars
$20.00
Nothing you idiot! If it doesn't have a serial stamp on it, it's gay and worth crap!
It's still worth $2 in Canada.
It's worth $50.
Worth about 4 to 10 dollar depending on condition