The currency we see most people use in ninjago is coins with a square and a hole in it. If you have literally bought or watched someone buy anything, you know that no one uses coins. So i'll make up the currency Ninjagan Dollar (NGD). The symbol would be an N with two vertical lines through it. Credit/ Debit card companies and banks include Ninjagan credit, Ninjagan card, Bank of Ninjago, etc.
