# Missing #

What's the missing number and why?

http://img18.imageshack.us/img18/2408/a89raetsel.png [Broken]​
[/URL]

Last edited by a moderator:

Related General Discussion News on Phys.org
drizzle
Gold Member
5 [and this just to submit the post, damn 4 characters! :grumpy:]

5 [and this just to submit the post, damn 4 characters! :grumpy:]
why?

drizzle
Gold Member
why?
21
23
25
27

I thought that too, but you beat me to it. You don't think there might be a pattern in the columns?

drizzle
Gold Member
24 22 22 28 hold on a sec!

drizzle
Gold Member
1st sum [raw]= 1st sum [column]-3
2nd sum [raw]= 2nd sum [column]+1
3rd sum [raw]= 3rd sum [column]+3
4th sum [raw]= 4th sum [column]-1

so I guess that works. But this puzzle could have more than one answer. When you add all of the number up you get 91. So the ? could be a 9, making the total a perfect square Another (and stupid) way to get 5:

Each row and column has two numbers that have 4 letters, hence the missing number must have 4 letters. Each row has an odd number of odd values, and each column has an even number of odd values. Hence, the missing number must be odd. The only choices being 5 or 9. Looking at the rows, no number is more than 3 away from its neighbors, hence, the number cannot be 9, and must be 5.

DaveE

Look at the total for each column and each row.

Column 1: 24
Column 2: 23
Column 3: ?
Column 4: 27

Row 1: 21
Row 2: 23
Row 3: ?
Row 4: 27

If you use 4, that means the 3rd row is 24 and the 3rd column is 21. Therefore there is a 1:1 ratio of the frequency of column sums to row sums.

..right?

drizzle
Gold Member

Look at the total for each column and each row.

Column 1: 24
Column 2: 23
Column 3: ?
Column 4: 27
Row 1: 21
Row 2: 23
Row 3: ?
Row 4: 27

If you use 4, that means the 3rd row is 24 and the 3rd column is 21. Therefore there is a 1:1 ratio of the frequency of column sums to row sums.

..right?
check it :)