Rousseau MusicPad helps you understand and use numbered musical notation. The seven-note keypad allows input of numbers (or ordinary notes) to the sound of an Italian harpsichord. Music can be played forwards or backwards. Buttons allow for key and octave change, accidentals, and formatting. Melodies can be imported from the iReal Pro app clipboard and exported to iReal Pro or to any app that understands Midi or MusicXML.

This system for Numbered Musical Notation (nmn) was invented by Geneva-born philosopher and composer Jean-Jacques Rousseau (1712-1778) and was first presented to the French Academy of Sciences in 1742. It is very similar to east-Asian "jianpu" simplified notation.