Original: The numbered keys used are "1", "4", and "7" for green notes, "2", "5", and "8" for red notes, and "3", "6", and "9" for yellow notes.
Simplified: The numbered keys used are "1", "4", and "7", for green notes "2", "5", and "8" for red notes, and "3", "6", and "9" for yellow notes.