Our fan Valeria M. in Spain asked us, how long would it take to run all the way around the world? Believe it or not, a few runners have already done it. Kevin Carr of England ran around Earth in…can you guess how long it took him? Weeks? Months? Years? He did it in an amazing 621 days! (One year has 365 days.) That’s a distance of about 25,000 miles if you ran the biggest possible circle. The question is, what would be the absolute fastest time if a person could run without stopping? Remember, Kevin had to sleep, eat, and rest his feet. As we’ll find out below, running without stopping would be way faster.
Wee ones: If you run 4 miles and your dog runs 1 mile farther, how far does your dog run?
Little kids: If you run 2 miles from home to the park, then 3 miles more to the ice cream shop, and finally 4 more miles home, how many miles do you run? Bonus: If you wanted 11 miles total of running, which part of that trip should you run again?
Big kids: If you could run 10 miles an hour for a whole 24-hour day, how many miles would you cover? Bonus: Then about how many days would it take to run the 25,000 miles around our planet?
The sky’s the limit: If Kevin finished this 621-day run in April 2015, in about what month and year did he start, and how old were you back then? (You can assume 30 days per month, and count from end of April so the 21 days beyond 600 don’t carry you over another month).
Answers:
Wee ones: 5 miles.
Little kids: 9 miles. Bonus: From home to the park, since you need 2 more miles.
Big kids: 240 miles. Bonus: About 100 days.
The sky’s the limit: In August 2013. He took about 20 months from the beginning of April. 12 months takes us to the previous early April, in 2014, and 8 months before that brings us to the previous August. As for your age, that’s different for everyone: August 2013 was 6 years 3 months ago, so subtract 6 years from your age, or 7 years if your birthday is between early August and mid-November!
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 before she could walk, 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.