Dogs may seem like they’re just fun, fluffy goofballs. But some dogs actually work real jobs, such as police dogs. They’re called the K9 unit, since it sounds like “canine,” which means “dog-related.” K9 dogs are usually German shepherds, like the dogs in this picture who are practicing behaving well by watching a cat without chasing it. K9 dogs train for a few hours every week, and can work for about 6-9 years. Then they can start chasing cats again.
Wee ones: Are there more cats or dogs in the photo?
Little kids: If a dog trains until age 3 and then works for 7 years, how old is the dog when he stops working? Bonus: If an 11-year old dog has worked for 9 years, how old was she when she started?
Big kids: If a dog starts training at 9:30 am each day for 8 hours straight, at what time does training end? Bonus: If 1/5 of the 15 dogs in the photo just can’t stand it any more and start chasing the cat, how many dogs sit still like they should?
The sky’s the limit: If in self-control training there are 5 times as many dogs as cats, and there are 24 animals in total, how many of each animal do we have?
Answers:
Wee ones: More dogs!
Little kids: 10 years old. Bonus: At 2 years old.
Big kids: At 5:30 pm. Bonus: 12 dogs, since 3 of the 15 dogs pounce.
The sky’s the limit: 20 dogs and 4 cats. If there are 5 times as many dogs as cats, then there are 6 total “sets” of animals that add up to 24. That means each set has 4 animals, giving us 1 set of 4 cats, and then 5 times as many dogs, or 5 x 4 = 20.

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.