It comes from Scott Kim, the puzzle maker for Discover Magazine. He has a 2010 page-a-day calendar just out called Mind Benders and Brainteasers. Here's one of the puzzles in it: 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?
Henry was here on Sunday and he worked out an answer almost immediately using jumps of 11:
50 61 72 83 94 (adding 11)
Then Ross read elsewhere that there are a total of four possible answers, so he wrote a computer program to find them all:
10 32 54 76 98 (adding 22)You will notice a critical fact in this account of how these answers were deduced: I had nothing to do with them. The only thing I provided was some off-hand comment about needing a number ending in zero. I think I could have solved it with enough time, paper, pencils, and hair to pull out. But luckily I didn't have to! (I don't have the hair to spare...)
18 36 54 72 90 (adding 18)
54 63 72 81 90 (adding 9)
In other news, the cookies are all packed and most have been given away already. I'm expecting a call from the Surgeon General to the effect that I'm an enemy combatant in the war against obesity.
2 comments:
By the way, and in my own defense, I programmed Blogger to post this at 3:06 this afternoon, which is says it did, but of course it didn't post until I manually told it to post.
Stupid Blogger.
The first answer I came up with was the 9 sequence (took about 5 minutes). Then I read that people had found a total of four solutions, I thought about it, and decided that my answer was good enough :-) Too much math for one Sunday.
Post a Comment