Received an email from a reader. Please feel free to contribute your solution/ideas by posting in the comments section of this thread. Thank you.

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I am a Primary 6 Student and have been reading your blog since P5. I would like to ask for your help in the 2 questions from Pei Hwa Presbyterian CA1 Math paper:

Paper2

Q18:

7 apples cost $4

9 oranges cost $11

James bought a total of 1000 apples and oranges for $999.

How many apples and how many oranges did he buy?

Q5:

297 digits are used to print the page numbers of a story book.

What is the number on the last page number of the story book?

Please help me as I have spent so much time trying to find the answers and still can't.

Thank you so much and happy new year.

This blog is managed by Song Hock Chye, author of Improve Your Thinking Skills in Maths (P1-P3 series), which is published and distributed by EPH.

## Tuesday, February 15, 2011

### Maths Qs from reader

Labels:
Mathematics

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## 2 comments:

Q5 Answer:

1 to 9 have 9 digits

10 to 99 have 180 digits

100 to 135 have 108 digits

9+180+108 gives 297 digits.

Hence the number on the last page number is 135.

Q18 Answer:

Let A = total numbers of Apples

and B = total number of Oranges.

( I used B instead of O )

(A/7)4 + ( B/9 ) 11 = 999

4A/7 + 11B/9 = 999

( 36A + 77B )/63 = 999

36A + 77B = 62937 ------ (1)

B + A = 1000

A = 1000 - B ------------ (2)

Sub (2) into (1)

36( 1000 - B ) + 77B = 62937

36000 – 36B + 77B = 62937

41B = 62937 – 36000 = 26937

B = 26937/41 = 657

A = 1000 – 657 = 343

So, James bought 343 apples and 657 oranges.

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