5 Pesos 60 Centavos Fuertes = 40 Chirolas

The denomination itself tells the story. "Chirolas" was a contemptuous slang term for the small copper coins that circulated in Argentina's interior provinces, and a banknote denominated in them — with the conversion spelled out explicitly — signals a deep institutional mistrust between Buenos Aires banking culture and the provincial populations these notes were meant to reach. The Banco Nacional was threading a needle between two monetary worlds that barely acknowledged each other.

PS#668 is among the more unusual fractional expressions in Argentine provincial banking, and surviving examples are genuinely scarce.