There is a bit of mythology revolving around John Lennon and his relationship to the number "9".
John Lennon was born on October 9, 1940.
His son, Sean Lennon, was born on October 9, 1975.
"#9 Dream", a track on his 9th solo album Walls and Bridges released 9/1974 made it to 9 on the US charts.
His famous avant-garde song on The White Album was called Revolution 9.
One After 909 was a song he wrote early in his carrer, but wasn't released until the Let It Be album.
His apartment in the Dakota Building which is located on 72nd Street, was 72.
If calculated on Liverpool time, Lennon was murdered on December 9 (the evening on December 8 New York City time).