[A footnote accompanying the story of Subhadda, an old ascetic who became the last person converted by Shakyamuni himself says:] This account contains a verse that is the oldest reference to chronology in Shakyamuni’s life: “At twenty-nine, I gave up the secular life in search of what is good, Subhadda, and fifty-one years have passed since then.” Seven years passed from the time that he left his father’s house until his enlightenment at the age of thirty-five, and he was active as a Buddha for forty-five years. (page 187)
The Beginnings of Buddhism