Monday, December 14, 2009

Weekend Edition Puzzle

While listening to NPR's Weekend Edition yesterday, I heard the following puzzle, which was created by Scott Kim:
Name five two-digit numbers that are evenly spaced out — like 32, 34, 36, 38 and 40 — in which all 10 digits from 0 to 9 are used once each. What numbers are these?
My son came up with one answer, which I thought was the only one, but when I gave it as extra credit to my students today as they were taking their exam I saw two other correct answers as well. Can you solve solve this puzzle? Can you come up with more than one answer?

After December 17 I will put the answers I am aware of in the comments section. No fair peeking until you've come up with a solution of your own! If you come up with one I do not have listed, please comment and let me know!

PS I've also posted this on my "Fun Math" blog. If you are interested in more things of this type, you might want to check it out at:

BY THE WAY, if you are reading this before noon on Thursday, December 17, you can still enter. Go to Weekend Edition at for details.


Steve B. said...

I found two sets that work, so far, so I'll wait to see what you have and compare. I must admit that I haven't thought that much about numbers in quite a while (other than adding up dart scores).

Heidi said...


Heidi said...

Here are a couple of possibilities:

54, 63, 72, 81, 90

10, 32, 54, 76, 98

I think I saw about 7 different ones as I graded exams - although some bent the rules a bit and used such things as 01 and 09 as two-digit numbers.