Why did Billy Crystal name his one-man show and autobiographical book 700 Sundays?

Answer 1

In his book, Billy Crystal writes about his family, beginning with his father. His father worked hard to support the family, holding down two jobs, working long hours, six days a week. Sundays was the one day of the week that the family usually spent together.

When Crystal was 15, his father died suddenly. He once did a calculation of how many Sundays they had spent together and he came to a number around 700, hence the name.