1 000 000 000 Pengő

Hungary's 1946 hyperinflation remains the most severe ever recorded. By late July 1946, the daily inflation rate exceeded 200 percent, and the pengő's total collapse required denominations that strained basic comprehension — the milliárd pengő (one billion) was not the ceiling but a midpoint in a cascade that eventually produced the 100 quintillion pengő note. The entire pengő series was withdrawn on 1 August 1946 and replaced by the forint at a rate so extreme the conversion figure itself became historically famous: 400,000 quadrillion pengő to one forint.

Endre Horváth both designed and engraved the note — unusually, a single hand responsible for the full execution — working under conditions where the practical lifespan of any new denomination was measured in days.