A# sixth/ninth chord
A#6/9 chord for piano with keyboard diagram.
Explanation: The A sharp sixth/ninth is a five note chord. Due to practical circumstances, however, the fifth (F) is often omitted and/or the chord is played inverted. The chord is abbreviated A#6/9.
Theory: The A#6/9 chord is constructed with a root, a major third, a perfect fifth, a major sixth and a major ninth.
Notes: A# - D - F - G - C