### Thursday, May 11, 2006

## 171. Bulletin board

A while back I asked for suggestions for the school bulletin board. A number of you asked what I ended up doing. I had my students choose a number and make a small poster for that number with information on that umber. I laminated them and put them up.

Here is some of the information from the posters (in the students' words:

- 0: There was no year zero.
- 1: 1 is the number of votes the German lost by when we voted what language we should speak, so we could have been speaking German now if we lost that vote.
- 6: There were six Beatles: Stu Sutcliffe who quit the band early to pursue art, Pete Best who was kicked out and replaced by ringo Starr. The others were Paul McCartney, John lennon, and George Harrison.
- 7: 7 is the highest number of eclipses that can happen in a year.
- 9: 9 is the smallest odd composite number.
- 10: The number of commandments.
- 11: The sun spot cycle repeats about every 11 years. Sun spots are dark spots on the surface of the sun. They occur more often during the active phase of the sun spot cycle. The spots have intense magnetic fields which are associated with magnetic storms on earth. Radio reception on earth is also affected by the sun spot cycle.
- 12: My best friend is twelve.
- 14: The humble woodlouse has 14 legs arranged as seven pairs. The hallucigenia also had 14 legs but is now extinct.
- 15: The longest word that doesn't repeat any letters is uncopyrightable which has 15 letters.
- 17: There are exactly 17 ways to express 17 as the sum of 1 or more primes. 17 is the only integer which is equal to the number of prime partitions of itself.
- 21: The total number of spots on a normal die.
- 22: Theoretically the minimum number of moves required to solve a Rubik's cube from any position.
- 28: 28 is a perfect number. A perfect number is a number that is equal to the sum of its proper factors. The numbers that divide evenly into 28, besides itself, are 1, 2, 4, 7, 14. 1+2+4+7+14=28. Perfect numbers include 6,28, 496, 8128, 33550336.
- 53: The late Diana, Princess of Wales, was on the cover of People magazine 53 times.

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Choco, I think you misunderstand the statement.

It is saying that, given a Rubik's cube, it can be solved in 22 moves or fewer. 22 is the minimum such number.

Sort of like the four-color theorem for maps. Only this is the 22 turn theorem for Rubik's cubes.

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It is saying that, given a Rubik's cube, it can be solved in 22 moves or fewer. 22 is the minimum such number.

Sort of like the four-color theorem for maps. Only this is the 22 turn theorem for Rubik's cubes.

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