Fatto generale: 40 is the number of years of marriage as the ruby wedding anniversary.
Fatto matematico: 40 is a repdigit in base 3 (1111) and a Harshad number in base 10.
Trivia: 40 is the number of positions on a number of radio countdown programs, most notably American Top 40 and American Country Countdown.
Data storica: February 9th is the day in 1973 that Biju Patnaik of the Pragati Legislature Party is elected leader of the opposition in the state assembly in Orissa, India.