Indiana Jones and the Great Circle "Monkey Business" mission involves finding keys rather than a numerical safe code. However, if you are looking for the code for the Sukhothai safe
Indiana Jones and the Great Circle: "Monkey Business" Mystery monkey business safe code top
If you are looking for safe codes in other games with "Monkey Business" levels or themes: Indiana Jones and the Great Circle (Sukhothai): Voss’s gold stash (top floor): 5484 [1] Game of Wits mystery: 3186 [1] Indiana Jones and the Great Circle "Monkey Business"
Let's say you find clues that suggest a monkey's favorite numbers or sounds could unlock a safe: monkey business safe code top