According to the search results, the denomination of Monopoly money that is green is $20. In the standard version of the game, Monopoly money consists entirely of notes, and the notes come in different colors representing different denominations. The modern Monopoly game has its Monopoly money denominated in $1, $5, $10, $20, $50, $100, $500, and (in some editions) $1,000, with all but the last two paralleling the denominations in circulation in the United States.