Do Not Disturb

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

Do Not Disturb

November 1, 2013

People collect all kinds of items: coins, stamps, anything shaped like a cow. They collect to see how many of the item they can track down in total, and how many different versions of it. Well, one guy decided to collect Do Not Disturb signs from hotels. If you’ve ever stayed in a hotel, you know that it’s a little plastic sign you hang on the knob outside your door to let people know they shouldn’t knock. Somehow, Jean-Francois Vernetti has managed to collect 11,111 of these signs. He’s been at it since 1985, when he found one sign that was spelled wrong and decided to start collecting others as a joke. His collection, which he’s basically stolen, comes from 189 countries and holds the Guinness world record. The real question is, how much did all those airplane tickets cost him?

Wee ones: If Vernetti checks into a hotel in a city, but then stays in 4 other hotels there that week just to collect more signs, how many hotels did he stay in?

Little kids: If Vernetti stays in 3 different hotels on every trip, and collects 3 signs from each, how many signs does he get?  Bonus: If he also got 5 chocolates on his pillow at each hotel (which some hotels do as a welcome), how many chocolates did he get?

Big kids: If of his 11,111 signs 5,000 are in English, 6,000 are in Spanish, and the rest are all in their own different language, how many languages do those signs cover?  Bonus: Vernetti had to travel a lot to collect that many in less than 30 years. If he stays in a new hotel every other day, starting on New Year’s, how many signs can he collect in 1 year?  (Reminder: A year has 365 days.)




Wee ones: 5 hotels.

Little kids: 9 signs.  Bonus: 15 chocolates.

Big kids: 113 languages – remember to count the English and Spanish!  Bonus: 183 per year: half of the first 364 days, plus the 365th day (whether or not it’s a leap year). By the way, at that rate he still would have gotten only about 5,000 signs.

And a big thank-you to Darci-Anna V. for inspiring this BMP!

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About the Author

Laura Overdeck

Laura Overdeck

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking while still in diapers, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.

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