Do you know which board game has 40 spaces? What pro sports teams have 40 players? Upgrade your knowledge about the number 40 here.
This Is 40: Bizarre Factoids About the Number 40 You Never Knew
Updated on Jun. 20, 2025
Forty. When it comes to age, the big 4-0 is legendary—that milestone birthday when you hit your stride (or get a face tattoo, ahem). But have you noticed that your 40th is not the only situation where the number 40 holds special significance?
This magical number pops up in board games, great books (including the Bible) and household-product origin stories. Is it all just a coincidence … or is there something unique about the number 40? We combed through popular culture, literature and history for the most fascinating facts about 40, so you could decide for yourself. Read on, and get ready to have a new favorite number.
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1. Forty is the only number in English whose letters appear in alphabetical order.
2. Minus 40 degrees, or “40 below,” is the only temperature that is the same in both Fahrenheit and Celsius.
3. When the bubonic plague gripped Europe during the Middle Ages, ships would be isolated in the harbor for 40 days before passengers or goods could go ashore. The Italian word for 40 is quaranta—hence, quarantine.
4. There are 40 spaces on a standard Monopoly board.
5. Forty is the maximum number of players a Major League Baseball team can have on its roster at once (including players on the injured list).
6. Forget “nine months”—a typical pregnancy actually lasts 40 weeks.
7. It took chemists 40 attempts to develop the magical spray we know as … wait for it … WD-40 (full name: Water Displacement, 40th formula).
8. In literature, 40 is the number of thieves Ali Baba clashes with in The Arabian Nights.
9. Also, 40 is the number of winks Dr. William Kitchiner suggests taking for a perfect nap.
10. In religion, 40 seems to be shorthand for “a long time.” Jesus spent 40 days fasting in the wilderness being tempted by the devil. The great flood lasted 40 days and 40 nights. The Jewish people wandered the desert for 40 years.
11. And if you need more evidence that 40 sounds like a lot, please see the standard American workweek: 40 hours.
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At Reader’s Digest, we’re committed to producing high-quality content by writers with expertise and experience in their field in consultation with relevant, qualified experts. We rely on reputable primary sources, including government and professional organizations and academic institutions as well as our writers’ personal experiences where appropriate. We’ve gone the extra step and had Marcy Lovitch, a fact-checker with 20-plus years of experience researching for national publications including Marie Claire, Good Housekeeping, Family Circle, Glamour, Seventeen, Real Simple, Forbes and InStyle magazines, verify that all quotes are attributed correctly and have credible sourcing. Read more about our team, our contributors and our editorial policies.
Sources:
- The Weather Channel: “Why Minus 40 Is a Magical Number in Weather”
- Britannica: “Middle Ages”
- The St. Augustine Record: “10 things you might not know about Monopoly”
- MLB: “40-Man Roster”
- Britannica: “Ali Baba”
- Gutenberg.org: “The Project Gutenberg E-book”
- United States Conference of Catholic Bishops: “Matthew: Chapter 4”
- U.S. Department of Labor: “Fact Sheet #22: Hours Worked Under the Fair Labor Standards Act (FLSA)”
Originally Published in Reader's Digest
