## Monday, February 23, 2009

### Odds and 'Even' More Updates Week of 2-23-09

World Math Day '09
On March 4th, there will be the biggest online math contest on the planet! Registration and practice is now open for this event. Unite with students and schools from around the world to set a new world record! The Challenge - to correctly answer more than 182,445,169 questions in 48 hours.

- An Alternative Carnival of Math for PreK-12
Congratulations and Best Wishes to Denise at let's Play Math for this ambitious undertaking. Her inaugural edition is now up and running and I rate it a 10++++. She has links to nearly 20 math blogs and does justice to every one of them. Denise will need our support to keep this going.

Do any of you recall that I originally proposed a similar split in the 10th Edition of the Carnival of Math? It took Denise's courage and talent to make this a reality.

Dynamath - A New Student Math Blog
The author, currently a high school student and a former student of mine, goes by the moniker, Blabbermath. She introduced me to her blog a few days ago and I emailed her my comments and thoughts about her first few posts. She exemplifies everything I always looked for in that special student -- curiosity, insight, fearlessness in following her thought processes as far as they will take her and she is a darn good problem poser not to mention a talented writer. Try some of her challenges. I warn you - it can be addictive!

So who noticed the Amazing Decimal-Fraction Calculator in the sidebar? Surely you've always wondered about the pattern in the decimal representation of 1/9801? Now you can explore more decimal places than you ever thought possible:
1/9801 = 0.000102030405060708091011121314151617...
So when does this pattern start repeating? Go to the link in the sidebar to find out, then explore on your own...

1800-TEACHER.com Singapore's Education Network

Here's the invitation and terms from the authors of the site:
These worksheets are “school examination papers” contributed by parents and students over the years. The information contained herein is in the public domain. These worksheets are provided by 1800-TEACHER as a service to the community. You may download or print these worksheets for personal use only.

You need to register for free before you can download but it is worth it. For copyright reasons, I will not reproduce any questions here but I strongly urge you to look at the content and levels of difficulty of these assessments for the "primary" grades.

Pat's Blog
Pat Ballew has an excellent math blog and he and I often cross-reference each other. Pat expanded on the contest problem I posted the other day with a wonderful extension. This is a great question for your stronger 2nd year Algebra students. Building on each other's ideas is what Web 2.0 is all about! Thanks, Pat...

Sean Henderson said...

Nice problem of the day for today. I gave it to my trig class as extra credit, just at random, but I doubt any of them will try it, since we haven't really talked about this kind of proof and it's not really a 'trig' concept proper. I did it myself, actually in a different way than you did. I multiplied all of the terms out and used summation notation and the properties of 'sum of squares' and 'sum of cubes' to get to an answer. Worked pretty well, and for me at least it was an easier method to spot than the telescoping sequence you suggested.

Dave Marain said...

Sean,
I like these as you do and your method makes sense. The telescoping method is far from transparent, however, you may want to share it because of its utility in working with special summations in calculus.

Please understand: I am NOT the author of these questions! They are provided as a "gadget" (widget) by Blogger. The actual author is someone named Michael Boyle. I think I know who he is and, when I confirm that,I want to give him acknowledgment he deserves for these great questions!

Sean Henderson said...

Ah. That makes sense. I just assumed the box itself was a gadget and you had to provide all of the questions. How lucky of you not to have to come up with a new one each day.