Between October 1, 1993 and January 24, 1995 prices increased by 5 quadrillion percent. This number is a 5 with 15 zeroes after it.
So writes Thayer Watkins, Ph.D., in “What Happens When A Paper Currency Fails? The Worst Episode of Hyperinflation in History: Yugoslavia 1993-94.”
(Thanks to investigator Gill Vrebel for bringing this to our attention.)