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 June 9th, 2014, 10:15 PM #1 Senior Member   Joined: Nov 2013 Posts: 160 Thanks: 7 This math question from an admissions test for an elementary school in Hong Kong is going viral in China. According to ChinaSmack, it was the second-most-popular post on Chinese microblogging site Sina Weibo on June 5, when it was published. The question was part of an admissions test for first-graders. They had 20 seconds to answer. Can you solve it? From Sina Weibo: "What takes an elementary school student just seconds to do; takes a high school student several minutes; takes a college student half and hour and up; and takes a Ph.D a lifetime…" Last edited by skipjack; April 16th, 2015 at 05:54 PM.
 June 10th, 2014, 05:57 AM #2 Member     Joined: May 2014 From: India Posts: 87 Thanks: 5 Math Focus: Abstract maths! Solved it easy! Maybe I'm an elementary school student. It's quite simple. Look at it upside down because the car parks that way. Answer is L8, which is upside down for 87. :P Last edited by skipjack; June 11th, 2014 at 09:07 AM.
June 10th, 2014, 07:28 AM   #3
Senior Member

Joined: Nov 2013

Posts: 160
Thanks: 7

Quote:
 Originally Posted by Rishabh May be I'm an elementary school student. It's quite simple. look at it upside down because the car parks that way. Answer is L8 which is upside down for 87. :P
How long time did it take for you to solve the puzzle?

I admit, for me it took a little more than 20 seconds. But I am not an
elementary school student.

 June 10th, 2014, 11:07 PM #4 Senior Member   Joined: Apr 2014 From: UK Posts: 954 Thanks: 342 Well, it turns out I was studying for a PhD and didn't even know it! edit: typo
 June 11th, 2014, 04:48 AM #5 Member     Joined: May 2014 From: India Posts: 87 Thanks: 5 Math Focus: Abstract maths! Thus one teaches a very important lesson. Sometimes we foolishly assuming things as complex and burn our brains out when actually it may be in fact be very simple. I did it fast. I knew it could not be a series because it was for grade one and your quote from ChinaSmack explicitly tells that. Using common sense (not pen and paper), it is easy to think that successive numbers only form car parking slots. And then suddenly it struck me! It is a wonderful question. Highly stimulative.
 June 11th, 2014, 06:11 AM #6 Math Team   Joined: Apr 2010 Posts: 2,780 Thanks: 361 My strategy was: how can these numbers differ by 1 or 2 from left to right or right to left. I see I was not alone there
 June 11th, 2014, 06:23 AM #7 Senior Member   Joined: Nov 2013 Posts: 160 Thanks: 7 I almost gave up after one minute. It was irritating for me why there is number 06 in a wrong slot if the numbers are in increasing order. Nevertheless I just randomly chose the number 90 for the empty slot because it seemed appropriate if the numbers were in increasing order, and I noticed that it is the same as 06 turned upside down, and then I immediately saw the solution. I would say that my strategy was trial and error. It took me more than one minute, but it was just a lucky guess by myself. Otherwise I could have given up, because it seemed hopeless.
 June 11th, 2014, 08:58 AM #8 Math Team   Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 14,597 Thanks: 1038 ?,M,T,W,T,F,? After an hour: Jack Adult says "I quit"! After 2-3 seconds: Li'l John Child says "Sunday, Saturday"
 June 11th, 2014, 09:06 AM #9 Global Moderator   Joined: Dec 2006 Posts: 20,927 Thanks: 2205 The answer is 87. Why would one give it upside down?
 June 11th, 2014, 10:48 AM #10 Senior Member   Joined: Nov 2013 Posts: 160 Thanks: 7 I got another puzzle. It is taken from the book Higgs Force by Nicholas Mee. The question is: What shape goes in the empty square in the grid shown below?

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# hong kong elementary school admissions test question #21 on november 28 2013

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