10 000 000 Pengő

Hungary's postwar hyperinflation was among the worst ever recorded, and this 10 million pengő note from 1945 was already functionally worthless by the time it reached circulation. The Magyar Nemzeti Bank was printing denominations in the tens of millions — and soon after, the hundreds of millions, billions, and eventually the milpengő and b.-pengő series — simply to keep pace with a price level that was doubling roughly every fifteen hours at the peak in mid-1946.

The pengő was ultimately replaced by the forint on 1 August 1946, at a conversion rate so extreme — 400 octillion pengő to one forint — that it remains the largest denomination redenomination in monetary history.