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Monday, January 26, 2015

Problem of the Week

Like the start of each week, we have posted the following problem on our Facebook, Twitter, and Google + pages. We found it in the archive on and we challenge you to warm up your math muscles this cold Monday morning.

Click the picture to enlargen!

I solved the problem for this week pretty quickly. It just took a pen and paper and a little logic. Here's my solution and thought process after the jump...

Click the picture to enlargen!

So we can see that our two discs each have a 5 and an 8 on a face. The reverse of the disc with 5 is 2, and the reverse of the disc with 8 is 9. 

Did you solve this problem a different way? Have any questions about the math shown here? Let us know in the comments!


  1. I went through the same options, but in my head. This one was extremely easy.

    1. I agree, this one was easy. But we do like to have a variety! Thanks for commenting!

  2. Funny. I did it in my head and came up with 6 on the other side of the 5 (6 + 8 = 14) and 5 on the other side of the 8 (5 + 5 = 10 and 5 + 6 = 11).

    Am I wrong? Or are there two sets of possible answers here?

  3. Hi Michele, your answer would be correct if not for the qualification in the problem. It states that there are four different numbers. Thanks for your comment!