One (Harry Nilsson song)

"One" is a song written by Harry Nilsson and made famous by Three Dog Night whose cover in 1969 reached #5 on the Billboard Hot 100. The song is known for its opening line "One is the loneliest number that you'll ever do". Nilsson wrote the song after calling someone and getting a busy signal. He stayed on the line listening to the "beep, beep, beep, beep..." tone, writing the song. The busy signal became the opening notes of the song.