Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now: https://www.khanacademy.org/economics-finance-domain/core-finance/money-and-banking/banking-and-money/v/banking-5-introduction-to-bank-notes Introduction to bank notes (which you are more familiar with than you realize). More free lessons at: http://www.khanacademy.org/video?v=cNFLqhU4MN0