# 3,500-Ton Bath Toy

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.

# 3,500-Ton Bath Toy

November 5, 2014

When a big new warship is built for our Navy, it’s built on land, of course – but then it somehow has to get to the water. And shoving a 3,500-ton ship off the dock sure doesn’t sound easy. There are a couple of ways to do it, but it turns out the builders can just tip the boat off a ramp and let it plop into the water, like a bath toy. As we see in this video, last month Lockheed Martin launched the USS Detroit in that way: the ship hits the water at a crazy angle, but because of the way the weight of the ship is balanced, the boat eventually sloshes back and forth until it’s upright. Given that the ship cost \$360 million to build, they wouldn’t do this unless they knew it wouldn’t break the boat!

Wee ones: This USS Detroit is the 6th ship to take that name. Can you count them off from 1 to 6?

Little kids: If this is the 6th USS Detroit, how many ships have had that name before this one? Bonus: No one is on board a ship when it’s launched like this – they’d definitely get hurt. If before launch 13 builders and 2 curious kids are on board, how many people have to get off the boat?

Big kids: If they started building the ship in November 2012 and launched it in October 2014, how many months did the project take? (Assume they both started and ended mid-month.)  Bonus:How much is 3,500 tons in pounds, anyway? (Reminder: One ton equals 2,000 pounds.)

Wee ones: 1, 2, 3, 4, 5, 6.

Little kids: 5 ships.  Bonus: 15 people.

Big kids: 23 months, 1 less than 2 full years.  Bonus: 7,000,000 pounds (7 million).

### 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.