If you don’t do the math when you’re building something, you could get a big bad surprise. Back in 1919, a guy named J.D. McMahon told people he was building a “skyscraper” with a height of 480… but he never said 480 feet. So he built a skyscraper 480 inches tall, which comes to only 40 feet! That cost him a lot less money to build, and he kept all the leftover money. The Newby-McMahon Building still stands today as the world’s shortest, silliest skyscraper.
Wee ones: Most skyscrapers look like a rectangle from the side. How many sides does a rectangle have?
Little kids: Which is taller, a 40-foot tall building or a 400-foot tall building? Bonus: If they started building this little building in February 1919 and took 3 months, in what month did they finish?
Big kids: If the building should have cost $2,000, but people gave McMahon 12 times as much money to build it, how much money did they give him? Bonus: If your house is 24 feet tall and shrank to 1/12 that height, how tall would it be — and how would it look next to you?
Answers:
Wee ones: 4 sides.
Little kids: The 400-foot building is taller. Bonus: May of 1919.
Big kids: $24,000. Bonus: 2 feet, which is probably shorter than you!

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.