Is it possible you remembered the number 24 from film boxes made in Europe or made for European customers? In many European countries a logarithmic counting was used. Till end of the sixties most films showed only DIN (Deutsche-Industrie-Norm), later they had both values, and only end of the eighties/beginning of the nineties there were ASA values only printed on the boxes.
Before WWII, the units were "Grad Scheiner" (Scheiner Degrees), after WWII they became an industrial standard and were renamed in DIN, and the neighbouring countries followed suit.
ASA25 = DIN15
ASA50 = DIN18
ASA100 = DIN21
ASA200 = DIN24
ASA400 = DIN27
.....
The picture is the case of a consumer grade Kodacolor VR200 from 1999. It still shows the 24.