Q&A - PSLE Math

[tianzhu]

Belle2011:

Dear tianzhu,

Once again, thanks very much for your solution.

Cheers,
Belle.

Hi

You're welcome.

Best wishes

[INNOVATE]

tianzhu:

Hi Dharma


Good Morning.

Wishing you a fabulous 2011.

Perhaps, another way to solve this question in an algebraic way is to consider ab as equal to a single unit

4500 + ab – (45-ab) = 4489
4455 + ab + ab =4489
ab = 34
Hence ab = 17


This type of question, guess and chk method is recommended than using algebra. The latter should only be used at sec 1 level. Pupils need to come up with the ans fast under exam condition.

As it is not too complicated, the mark awarded is probably btw 2/3 marks.

However for this question, it isn’t too tedious to solve it with logical reasoning and Guess and Check for students who prefer not to use algebra.

Best wishes

[Dharma]

tianzhu:

Hi Dharma


Good Morning.

Wishing you a fabulous 2011.

Perhaps, another way to solve this question in an algebraic way is to consider ab as equal to a single unit

4500 + ab – (45-ab) = 4489
4455 + ab + ab =4489
ab = 34
Hence ab = 17

However for this question, it isn’t too tedious to solve it with logical reasoning and Guess and Check for students who prefer not to use algebra.

Best wishes

Hi Tianzhu,

Wishing you a wonderful New Year too!

Thanks for your neat and elegant solution.

[tianzhu]

Lynn2:

May I know anyone here can share where can I find very challenging questions for Circles?thanks


Rgds
Lynn

Hi

How about those questions from top schools past years papers?

They should offer sufficient practices to prepare for PSLE Maths.

Best wishes

[Rockdiva]

so can i say that the p6 qns are mostly on assumptions and logic thinking and no distinct formula to work it out?

[autolycus]

Rockdiva:

so can i say that the p6 qns are mostly on assumptions and logic thinking and no distinct formula to work it out?

Yes, because for most schools at P6 nowadays, algebra isn't taught as the main method of solving problems. That's why my solution doesn't use algebra. And that is why 'distinct formulae' are not normally the way to go...

[shurley197323]

There are 1000 desks in an examination hall.Mages numbers all the desk in running order starting from 1. What is the total number of digits she writes? Besides doing manually listing out 1 by 1. Is there any shortcuts or formula for this ? Pls help. Thank you.

[tianzhu]

shurley197323:

There are 1000 desks in an examination hall.Mages numbers all the desk in running order starting from 1. What is the total number of digits she writes?

Hi

Hope this helps.

1 to 9 ------ 9 digits
10 to 99 ------ 180 digits
100 to 999 ------ 2700 digits
1000 ------ 4 digits

Total number of digits ------ (9+180+2700+4) ------- 2893

Best wishes

[shurley197323]

Thanks for your help. Tianzhu

[tianzhu]

shurley197323:

Thanks for your help. Tianzhu

Hi

You're welcome.

Best wishes