There is a four-person disc on the screen of Adventure in the Red Castle. Choose a number for each disc, and the English on the wall is: ROMANES EUNT DOMUS. How to live?

1009, you read the wrong keyword. Roman numeral mixing does not mean mixing Roman numerals, but mixing Roman numerals.

MIX = 1000+ 10- 1 = 1009

Romanes Eunt Domus comes from "Star of the World", which means "Roman, your mother wants you to go home for dinner". The protagonist in the film was sent by the Jewish resistance to brush anti-Roman slogans and was caught by the Roman centurion. As a result, the centurion picked out a bunch of grammatical mistakes from the three words, and then punished the protagonist for brushing them hundreds of times in the city. ...