## Q&A - PSLE Maths - Highlights ONLY

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### Q&A - PSLE Maths - Highlights ONLY

[Moderator's note: This thread is only for PSLE Math questions with "certified" answers. Please contribute challenging questions together with their solutions in this thread. All discussions about these questions should be posted in the Q&A - PSLE - Math thread. Thank you for helping keep this thread clean as a reference for parents/students in the community.]

Original Title: Highlights in Past Years' PSLE Maths

I have heard that the PSLE questions published commercially do not always contain the past years' challenging questions. I hoped that by creating this thread we can consolidate the "highlights" over the years so that this will be a resource for each year's parents in their quest to prepare their children for PSLE maths.

2000 (1st year I know of with an uproar)

What is the last digit of the sum 1 + 2 + 3 + ... + 5 + 96 + 97
Ans : 3

After 2000, every schoolkid should have been taught how to do this question by p6. Therefore such questions no longer pose a threat unless...

__ __ __ ___ B
|__|__|__|__| North
|__|__|__|__| -->East
|__|__|__|__|
A

How many ways are there to get from point A (bottom left corner) to point B (top right) if you are only allowed to move an odd number of steps northwards(up) each time and an even number of steps eastwards (right) each time.

Ans: 4
This is similar to those kinda "route/path finding" questions experienced by students in maths competitions or exams, but there is a significant difference in the underlying math concept. The conventional path finding questions involve no restrictions on restrictions by passing through certain points.
Given this small size, the answer is likely to be small, therefore students are better off brute-forcing, as the mathematical working required to deduct logically all possible routes is too time-consuming and probably beyond the average student.

When the famous Andrew Er's Challenging Problems was published in 2001, he posed a similar problem too.
A squarish grid, 6 squares across, 6 squares down, seeking the number of ways from X (the top left hand corner) to Y (bottom right hand corner) if only allowed to move an even number of steps southwards (at a time) and an odd number of step eastwards (at a time).
Answer given in the book : 5

The present's edition contained a similar but simplified version.

Trivia : These 2 PSLE questions were posed to 5 presidents of international MENSA associations (whose combined IQ exceeds 800) and Mr Robert Beaty (president of American Mensa) solved the first problem in 15 secs and took more than 4 mins to answer the second one.
Parents complained that the questions require higher-order thinking skills not taught.

2005

http://www.math.nus.edu.sg/aslaksen/papers/PSLE2005.pdf
Here you can see the infamous question 13 (the flawed question).

2007
http://sc-math.com/math-talk/math-psle07.php
http://kofplayer.wordpress.com/2007/10/ ... -too-hard/

2008
http://www.jamesangtutors.com/forum/vie ... 9288b33365
http://psle2008.blogspot.com/2008/10/qu ... ual-5.html

2009
http://psle2009.blogspot.com/2009/10/ps ... tions.html

For our own community's discussion and numerous solutions view the psle 2009 maths thread
http://www.kiasuparent.com/kiasu/forum/ ... php?t=5906

Miscellaneous
http://www.amt.canberra.edu.au/icmis16psinyeap.pdf
This contains some psle questions published by the SEAB, worth a look.

If anyone else has any idea(perhaps you did a newspaper cutting ) about other questions in 2005 or whether theres any uproar in the years 2002-2004 feel free to add on.[/img]
Last edited by CoffeeCat on Wed May 19, 2010 9:25 pm, edited 1 time in total.

CoffeeCat
BrownBelt

Posts: 516
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http://psle2009.blogspot.com/2009/10/ww ... -psle.html

the famous 10 PSLE questions posed to the 31 year old banker with degree and 12 year old PSLE student to solve on Channel News Asia. The banker gets 1/10, the student gets 4/10. Try them!

James Ang
KiasuGrandMaster

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