15 Kyats

The 15 Kyat note was issued because Ne Win, Burma's military ruler, considered 9 and its multiples to be his lucky numbers — a conviction rooted in personal numerology that directly dictated monetary policy. The series of 15-, 35-, 45-, 75-, and 90-Kyat denominations that appeared in 1986 replaced perfectly functional notes of standard value, causing immediate practical chaos in daily commerce. Within two years, the 1988 demonetization rendered most of these same notes worthless overnight, a decision that helped trigger the pro-democracy uprisings of that year.

The print run of roughly 12 million is modest, which combined with mass hoarding and subsequent panic exchanges makes genuinely circulated examples harder to find than uncirculated ones.