Must be the Dog

Logic Level 2

A newspaper is printed on several sheets of paper and then folded down the middle. Each piece of paper will thus contain four pages.

On glancing through the newspaper whose back page is 28, you noticed that a sheet is missing. One of the missing pages is page number 8. What are the other three missing pages?

Write your answer in the increasing order of the number of pages. For example, if you think that pages 4, 11, and 25 are missing, then your answer will be 41125.

The answer is 72122.

4 solutions

Caleb Townsend
Mar 26, 2015

The first missing page is the most obvious as it is the other side of page $8.$ It is an even number so the other side of it is page $7.$

If you read the newspaper, you have probably noticed that each piece of paper actually contributes $4$ pages total, since it is folded down the middle. Layer $1$ contains pages $1, 2, 27, 28,$ layer $2$ contains pages $3, 4, 25, 26,$ and so on. Layer $4,$ the paper that contains pages $7$ and $8,$ also contains pages $21$ and $22.$ The concatenation of these pages is $\boxed{72122}.$

i put in 782122....what an idiot i am

Martin Le - 6 years, 2 months ago

I know that feeling too well😂

Grahamové Pečivo - 5 years, 2 months ago

782122

layer

Kaleem Kħặŋ - 6 years, 2 months ago

The problem asks for the concatenation of the three missing pages, referring to the three which are unknown.

Caleb Townsend - 6 years, 2 months ago

Explained very nicely. Thanks.

Sandeep Bhardwaj - 6 years, 2 months ago

Low Pei Zuo
Mar 27, 2015

Each piece of paper consist of 4 pages but 2 large page if unfold. On each large page, the two page numbers sum up to 29, example:1+28, 2+27, and so on.

The first missing page is 7. Therefore the other two are 29-8=21 and 29-7=22.

I followed the same logic - simplest way to do it.

Steven Linnell - 3 years, 9 months ago

Ân Hồ Trọng Linh
Jul 24, 2015

Let describe all pages of newspaper like this

if page 8 is missing, It mean 7 + 21 + 22 is missing too

dude, u got the lower number backwards it should be 1 2 | 3 4 | 5 6 | 7 8 | 9 10 | 11 12 | 13 14 28 27 | 26 25 | 24 23 | 22 21 | 20 19 | 18 17 | 16 15 and since the question asked to be written in order, it'll be 7 21 22

u r lucky the number missing is 8, which is the middle paper if the missing number is 4 or 10 u'll get 3 17 18 instead of 3 25 26 or u'll get 9 23 24 instead of 9 19 20

Adriel Baruch - 5 years, 5 months ago

Michael Fitzgerald
Apr 20, 2018

last_page = 28
pages = []
for i in range(1,last_page+1,4):
    pages = [i, i+1, last_page-i, last_page+1-i]
    print sorted(pages)
    pages = []

[1, 2, 27, 28]
[5, 6, 23, 24]
[9, 10, 19, 20]
[13, 14, 15, 16]
[11, 12, 17, 18]
[7, 8, 21, 22]
[3, 4, 25, 26]

Must be the Dog

The answer is 72122.

4 solutions

0 pending reports