you have the numbers from 1 through 9. divide them into 3 groups so that each group has the same total after adding the digits in them..

Question

i got until: adding all the digits makes 45 and and divided by 3 so each will be 15, but what next? any method for that or do it by trial and error?

Answer 1

how about this one:

8 1 6
3 5 7
4 9 2

Each row, each column and each diagonal adds up to 15

Answer 2

Thanks a million!! but how did you get to it? is there a formula or method to deal with this kind of questions or just try to switch around and maybe stumble upon the right one? actually i was working on it, too and came up with 8 7, 9 6, 1 2 3 4 5 ,(as it did not say the groups has to have the same amount of numbers in them, only that the total has to be the same..)
your answer is very elegant

Answer 3

yes, there are methods and "formulas" to do these
Google "magic squares" and you will see all kinds of stuff
There is a very easy pattern for any odd-sized square which should be found in the first few results
Even-sized squares are a bit more difficult