P3 Problem Sums

by Joanne Lim
(Singapore)

Janet turned to some pages of a story book she was reading. Each of the pages had a 3-digit page number. The digits on the page on the left added to 14 and the digits on the page on the right added to 15. How many possible pairs of page numbers are there? (Note : the story book does not contain more than 300 pages.)


Zach's Answer:

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Jun 25, 2013
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One Additional Step Needed
by: Suzanne

I got 6 possible pairs of page numbers, not 11. To be accurate, you need to take the elimination of number pairs one step further. Because all books start with page #1 on the right, only pairs that have the even number on the left, and the odd number on the right would suffice. (I eliminated five pairs that did not fit this criteria for book protocol.)

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