This was first documented in the 1976 ethnographic film Number Our Days, directed by Lynne Littman.
Happy Days | Around the World in Eighty Days | Days of our Lives | Three Days Grace | Hundred Days | The Last Days of Pompeii | Death Valley Days | Days of Our Lives | Around the World in Eighty Days (novel) | Days of Heaven | 28 Days | Lucky Number Slevin | Reynolds number | Mach number | Days Inn | Seven Days Battles | serial number | Random number generation | International Standard Book Number | 30 Days of Night | prime number | Personal identification number | number | Days of Thunder | Two in a Million/You're My Number One | The Last Days of Disco | The Last Days | Social Security number | Rikki Don't Lose That Number | Prime number |