What do you get when you divide the circumference of a jack-o-lantern by its diameter? Pumpkin Pi! This week it’s time to carve pumpkins to make Halloween jack-o-lanterns. Before you can turn your pumpkin into a face though, you need to scoop out the seeds. A pumpkin holds hundreds of goopy seeds, but bigger pumpkins don’t always have more than smaller ones. Some say you can tell from the ridges on the outside, which line up with the “ribs” inside: more ridges = more ribs = more seeds. So when you’re picking a pumpkin to carve, do a little math up front and you can spare yourself a lot of goop.
Wee ones: What shape are the eyes on this jack-o-lantern?
Little kids: If you carve triangles for the 2 eyes and the nose, how many straight lines have you cut in total? Bonus: What if you make that nose into a hexagon instead?
Big kids: If your pumpkin has 11 ridges and your friend’s pumpkin has twice as many, how many does your friend’s pumpkin have? Bonus: If each ridge lines up with a row of 20 seeds, but every 9th ridge starting with the 9th lines up with 100 seeds, how many seeds does the ridgier pumpkin have?
Wee ones: Circles (although not perfect ones).
Little kids: 9 lines or sides. Bonus: 12 lines: a hexagon has 3 more sides than a triangle.
Big kids: 22 ridges. Bonus: 600 seeds. Only 2 ridges have 100 seeds apiece. They give us 200 seeds. The remaining 20 ridges give us 20×20 seeds.
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.