Mr. Lai’s Math Blog

student tutorials on math contest questions

2008 Question #21 (by Cassandra G., Christine P.)

Posted by elai on October 17, 2008




8 Responses to “2008 Question #21 (by Cassandra G., Christine P.)”

  1.   Ridzwan Nur Saidy Says:

    The steps in getting the solution was pretty straight-forward however the presentation of the method could have been better.

  2.   elai Says:

    Ridzwan. What would have made the presentation better? Be SPECIFIC.

  3.   Ridzwan Nur Saidy Says:

    The writing at times wasn’t really visible but other than that great job on the presentation

  4.   eric Says:

    can’t see and don’t understand!!!!!!

  5.   anfony changer Says:

    i caant see whats on the whiteboardd

  6.   christine pennington Says:

    sorry about the writing being a little difficult to read. On the left side of the board we just wrote out the question, which mr lai has provided on this page. However, on the right side of the board we added(in a column) the digits 1, 11, 101, 1001, etc. until there is a digit with 50 zeros in the middle. after getting the sum of those numbers we added the answers digits together.

  7.   prab grewal Says:

    hmm i couldnt watch all of it…it kept restarting at 32 seconds :( but i think if i had seen all of it…the accent and the mask would have really aided in my comprehension of the equation =D–> good job!

  8.   J Chan Says:

    I liked your simple and easily-understood method of using elementary-school adding to solve this freaky Part C problem. For example, you clearly showed us where the “62″ came from and where the “50″ came from, and all we needed to do was to add those 58 1s together(50+6+2) to find the sum of the digits. It was a great video despite all the flaws stated already by other students. =D

Leave a Reply

Create a free edublog to get your own comment avatar (and more!)

XHTML: You can use these tags: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

*
To prove you're a person (not a spam script), type the security word shown in the picture.
Anti-Spam Image