Saturday, April 4, 2009

小学奥数Mathematical Olympiad - Primary School

There are 10 men in a basket ball court, each of the man shakes hands with every other man once. How many "handshakes" are made? What if 100 men?

在篮球场上，有10个人互相握手，问共握了多少次手？100 个人呢？

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123456789101112131415 ... ... 9899100 has how many digit "1" ?
What if from 1 to 1000?

123456789101112131415 ... ... 9899100共有多少个1？
从1到1000呢？

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Actually this is  primary 3 / 4 level (standard 3 / 4 ) ...
这其实是小学 3 或 4 年级的奥林匹克数学问题。。。
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21 comments:

  1. Hou Yi's BLOGSunday, April 05, 2009 8:36:00 PM

    Answer 2

    1. eleven ones

    ReplyDelete
  2. 刘老师Monday, April 06, 2009 1:36:00 AM

    Thanks for trying!!
    but it is more than eleven =)

    ReplyDelete
  3. Hou Yi's BLOGMonday, April 06, 2009 5:52:00 PM

    o....Then is it twenty one?

    ReplyDelete
  4. Hou Yi's BLOGMonday, April 06, 2009 5:55:00 PM

    answer 1

    1. 90

    2. 9900

    don't know answer right a not..... xD

    ReplyDelete
  5. 刘老师Monday, April 06, 2009 6:30:00 PM

    Answer for question 1 is wrong,
    is less than 90...

    Answer for question 2 is correct!! Good!!

    ReplyDelete
  6. Hou Yi's BLOGTuesday, April 07, 2009 5:08:00 PM

    This comment has been removed by a blog administrator.

    ReplyDelete
  7. UnknownWednesday, April 15, 2009 9:10:00 AM

    This comment has been removed by a blog administrator.

    ReplyDelete
  8. UnknownWednesday, April 15, 2009 9:12:00 AM

    我是黄嘉仪的哥哥。

    ReplyDelete
  9. UnknownWednesday, April 15, 2009 9:13:00 AM

    pro le

    ReplyDelete
  10. 刘老师Friday, April 17, 2009 3:05:00 PM

    Ya pro :D
    Hou Yi, Heng you r right!

    I'm thinking, should I disable this comment posting, because if you all post all the answers then other people will not try to solve the problem themselves, they just see the answer..

    ReplyDelete
  11. Hou Yi's BLOGThursday, April 23, 2009 7:41:00 PM

    oo, k . It's fine with me...but don't know with Heng larh...

    ReplyDelete
  12. AnonymousSaturday, May 02, 2009 12:02:00 AM

    This comment has been removed by a blog administrator.

    ReplyDelete
  13. 刘老师Saturday, May 02, 2009 2:26:00 AM

    Anonymous, good!! You answered correctly!
    but I got to delete it, cause i don't want other to see answer, then they will not think..

    but I don't know who are you...

    ReplyDelete
  14. Carol TockThursday, June 11, 2009 10:08:00 PM

    haha. anonymous is Carol. 卓仪晴. 希望你还没把我忘了啦。嘻嘻

    ReplyDelete
  15. Carol TockThursday, June 11, 2009 10:11:00 PM

    aiya. ive been trained by the all mighty liew lao shi ma. best on da world! :P
    eh teacher. jun liang never get chosen meh?

    ReplyDelete
  16. 刘老师Friday, November 13, 2009 3:40:00 PM

    Carol Tock : Haha.. Jun Liang got Singapore Scholarship already loh...

    ReplyDelete
  17. 林哲辉Wednesday, December 09, 2009 10:00:00 PM

    我的答案：
    1）10人 - 45次
    100人 - 4950次

    2）1-100 - 21个1
    1-1000 - 301个1

    ReplyDelete
  18. Yew SuxuenFriday, December 11, 2009 11:36:00 PM

    Question number 1, the shake hand one.

    If 10 people, 45

    If 100 people, 4950

    ReplyDelete
  19. AnonymousFriday, February 11, 2011 3:12:00 PM

    刘老师，answer for 10个人要握100次对吗？

    ReplyDelete
  20. UnknownWednesday, October 24, 2012 3:46:00 PM

    hi,我是赖世豪！

    ReplyDelete
  21. AnonymousSunday, April 07, 2013 9:49:00 PM

    Q1:(a) 45 (9+8+7+....+3+2+1 = 9/2 X 10 =45)
    (b) 495 (99+98+97+ ...+3+2+1 = 99/2 X 100 = 495)
    [But above said 9900?? Why)
    Q2:(a) 21
    (b) How to solve??

    ReplyDelete

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