Slot Machines at Caesar's Palace Lake Tahoe. Nik Wheeler/Getty Images hide caption

Technology changes. Giordano Poloni/Getty Images/Ikon Images hide caption

People line up outside a bank to exchange old currency notes with new ones on November 10, 2016 in New Delhi India. Shams Qari/Barcroft Media via Getty Images hide caption

Anil Bokil, a mechanical engineer by training, had a plan for demonetization. He presented it to now Prime Minister Narendra Modi in 2013. Chhavi Sachdev /NPR hide caption

Economists have a yearly job market that works a little bit like speed dating. Gary Waters/Getty Images/Ikon Images hide caption

Former Federal Reserve Chairman Ben Bernanke. Katie Kramer/NBCU Photo Bank via Getty Images hide caption

English economist John Maynard Keynes attends the United Nations International Monetary and Financial Conference at the Mount Washington Hotel in New Hampshire. Hulton Archive/Getty Images hide caption

Healy Hall, the flagship building of Georgetown University's main campus in Washington, DC. MLADEN ANTONOV/AFP/Getty Images hide caption

#NationalCaramelDay AJ Mast/Invision for Werther's Original via AP hide caption

Tabs from Tigin Irish Pub in New York's JFK Airport. Irish Pub Company hide caption

There are tax collectors all over the globe are finding ways to get people to pay. aluxum/Getty Images hide caption

Giant stacks of paper. Martin Mistretta/Getty Images hide caption

Jason Blum, Blumhouse Productions Steve Henn / NPR hide caption

A note from the Second Bank of the United States. Museum of American Finance, NYC hide caption

A bread line forms outside of the Rescue Society in New York City in 1929. "Brother, Can You Spare a Dime?" directly confronted the hardship of the Great Depression. Wikimedia Commons hide caption