The highest-denomination banknote in history had twenty-one zeros

After World War II, Hungary went through the most violent hyperinflation ever documented — prices could double every few hours, and the government had to keep printing higher and higher denominations just to keep up with money's collapsing value.

The twist: in 1946, a banknote worth 100,000,000,000,000,000,000 pengő (one hundred quintillion) entered circulation — the highest denomination of legally issued paper money in world history.

Interestingly, an even higher denomination was printed — a billion trillion pengő — but it never actually entered circulation, because before it could be introduced, the whole currency was swapped out for a new one anyway.

The stakes: the entire episode of inflation lasted barely over a year — showing just how fast trust in money can collapse once a state loses control of its supply, and how absurd the numbers a central bank ends up having to print in that situation.