The notes in your pocket say they're legal tender for all debts public and private. Are they lying?
Despite a rise in cashless payments and a drop in customers drawing out cash, bank tellers might still have a future.
The evidence that €500 notes are used by criminals are strong. But there is no guarantee that scrapping them will crack down on illegal activity.
Do innovations like PayPal, Square, Apple Pay and Bitcoin spell the end of cash? How different countries are adopting new forms of financial tech.
How could a cashless economy make you gain weight? It's all about the pain in your brain.