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.

June 28, 2015

Do you know how to tell time? If you have a digital clock, the first number tells you how many hours have passed since noon or midnight, and the second number tells you the minutes since the hour started. But Bedtime Math fan Talie B. just showed us a new clock that turns telling time into a game. Instead of just saying 9:32 am, for each number it gives you an “equation,” or a way of combining other numbers. So it might say 3+6 for the hour (9), and 8 x 4 for the minutes (32). Better yet, it changes to a new equation every time, and it can use adding, subtracting, multiply, dividing, or even more than one of those at once. We’re guessing it’s named the Albert Clock after Albert Einstein, because you have to use your brain…if you do that every day, you’ll become really smart just like Albert!

*Wee ones:* If the Albert Clock says 7+1 for the hour, what hour is it?

*Little kids:* If it’s 4:00 and the clock uses a 2 and a 6 to tell you the time, what would it have to do to them? *Bonus:* What other number of hours could you make with just a 2 and a 6?

*Big kids:* Can you find a way to combine 5, 4 and 7 to get 31? *Bonus:* What’s the biggest number of minutes you can make with 2, 7 and 8? (Reminder if needed: the minutes part can run only as high as 59!).

*The sky’s the limit:* How many ways can the clock show 12 by multiplying 3 digits?

Answers:

*Wee ones:* 8:00.

*Little kids:* It would say 6-2. *Bonus:* You could make 8 (2+6), 12 (2×6), or 3 (6/2).

*Big kids:* 7 x 5 – 4, which is 35-4. *Bonus:* 58, by doing 7 x 8 + 2.

*The sky’s the limit:* These kinds of problems have lots of answers and you’re never quite sure when you’re done…but we got 15 different ways:

2 x 2 x 3, in any of 3 orders (just 3x2x2, 2x3x2, 2x2x3, since the 2s are identical)

4 x 1 x 3, in any of 6 orders (4x1x3, 4x3x1, 3x1x4, 3x4x1, 1x3x4, and 1x4x3)

6 x 1 x 2, in any of 6 orders (same patterns as above)

And thank you Talie for sharing this great clock story! And if you all have ideas for a fun story for our site, let us know!

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.

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