You should read about Brazil and our history of hyperinflation. The “old coin” OP is referring was Réis. Then it came the Cruzeiro (comes from cross and a constellation we see in our sky). Then the hyperinflation came and we had too many zeros in our day-to-day currency. So we cut 3 zeros and the currency became Cruzado (crossed). But it didn’t work, so we cut again and it became Cruzeiro Novo and then again Cruzado.
Finally, a team managed to control the inflation by making the economy flow with the dollar. We indexed the prices and salaries to an index called OTN and then BTN and finally this BTN became the Real.