1. Which Roman leader introduced the system of adding a leap day every four years, in 45 BC?

2. Under the Gregorian calendar, century years are leap years only if divisible by 400. So which is the next century year that will NOT be a leap year?

3. Roughly what are the odds of being born on 29 February: 1 in 365, 1 in 1,461, or 1 in 4,000?

4. In 1712, Sweden briefly had a date that no other country has used before or since, to get its calendar back in step. What was the date?

5. In which Gilbert and Sullivan operetta is the hero, Frederic, apprenticed "until his 21st birthday", only to find that, being born on 29 February, he has had only five birthdays?

6. According to Irish legend, which saint persuaded St Patrick to let women propose marriage on leap day?

7. On 29 February 1940, Hattie McDaniel became the first African American to win an Oscar. For which film?

8. On 29 February 1960, an earthquake destroyed much of Agadir. In which country is it?

9. On 29 February 1504, Christopher Columbus, stranded on an island, used his knowledge of an expected lunar eclipse to frighten the local people into feeding his crew. Which island?

10. On 29 February 1692, the first arrest warrants were issued in the witch trials of which New England town?

11. On 29 February 1880, the two teams of tunnellers digging a famous railway tunnel under the Alps met in the middle. Name the tunnel and the country it is in.

12. The siege of a European capital officially ended on 29 February 1996, after nearly four years. Which city?

13. A composer born on 29 February 1792 wrote an opera whose overture's final gallop became the theme of "The Lone Ranger". Name the composer and the opera.

14. An American inventor born on 29 February 1860 built punched-card tabulating machines for the 1890 US census. His company later became part of which famous computer company?

15. An Irish engineer born in County Clare on 29 February 1840 designed the first submarine formally adopted by the US Navy. Who was he?

16. Pope Paul III, born on 29 February 1468, commissioned Michelangelo's "Last Judgement" and called which great Church council in 1545?

17. Which major international sporting event was held only in leap years from 1896 until 2021?

18. The extra day was originally added by doubling the sixth day before the start of March. Which formal word for a leap year comes from the Latin for "twice sixth"?

19. In the 2010 romantic comedy "Leap Year", Amy Adams travels to which country to propose to her boyfriend on 29 February?

20. In Denmark, tradition says that a man who refuses a woman's leap-day proposal must give her how many pairs of gloves?