Hi all, Just got this as change at my local spanish bodega store.. It's what is called a Flipper Serial Number.. A number that when the bill is flipped upside down it can still be read as an actual number. 60069990 06669009 The condition is not the best with wear and folds but I don't care. It's mine and I love it!
I understand your question and I will clarify... Flipper is considered numbers such as 6, 9 and 0 that even when flipped over and upside down could still be seen as a number. It could be the exact same number upside down or not Lets make it shorter for example 669966 uside down is 996699 or 696969 uside down is 696969 see the difference?