# Time to Puck-er Up

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.

# Time to Puck-er Up

February 27, 2018

Every sport uses a different wacky ball or objects, from big orange basketballs to pointy footballs to feathery badminton birdies. But they’re all small compared to the size of the field for that game. So our friend and fan Elliot M. asked, how many hockey pucks can you fit in a hockey rink? Turns out those flat circle-shaped pucks are always 3 inches wide and 1 inch thick. But there’s more than one way to line up those pucks. As you see here, you can line up circles in neat rows and columns, where their centers form squares. But if you line up honeycomb-style so the centers make triangles, you fit more into the same area (instead of rows 1 puck-width tall, it’s the puck width times the square root of 3 over 2 (0.866), based on some very big-kid math).

So on just the 144-foot by 85-foot rectangle of a hockey rink, you can fit 576 rows with 340 pucks the “square” way, or 195,840 pucks…but honeycomb-style you can fit 665 rows of 340 pucks, or 226,143. Next time you line up cupcakes or apples in a box, you’ll know which way works best!

Wee ones: How many blue hockey pucks can you count in the “square” set on the left? Count as high as you can!

Little kids: If a puck is 3 inches wide, how wide is that square set of them?  Bonus: How many more pucks would you need to reach 1 foot (12 inches)?

Big kids: If you have a 12-inch by 12-inch square, how many pucks fit the “square” way?  Bonus: Better yet, what if we stand the pucks on edge in sideways stacks? They’re just 1 inch thick, so how many can you fit across 5 feet? (Reminder: A foot has 12 inches.)

Wee ones: 9 blue pucks.

Little kids: 9 inches, since it’s 3 x 3 inches.  Bonus: 1 more puck.

Big kids: 16 pucks, since you have 4 rows with 4 pucks in each.  Bonus: 60 pucks, since it’s 12 per foot x 5.

And coming tomorrow, a good deed to help a goose get loose!

### 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 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.