### Question #20

Thursday, November 26, 2009
Hello everyone! I am going to do question #20 (again) for those who didn't understand.

20) In a magic square, the sum of each row, column, and diagonal is the same. Copy and complete this magic square.

So first of all you find out the sum of the diagonal of the square.

And the sum is:

So now we know the sum, now we have to fill in the squares to make a sum of -2 1/2.

Next you have to do the easier ones first. The ones that have 2 squares filled in already.

You add up the two numbers and subtract it from -2 1/2

(-5/6)+(1/2)= -1/3
(-2 1/2)-(-1/3)= -2 1/6

1/2+(-1 1/6)= -2/3
-2 1/2-(-2/3)= -1 5/6

Then you do the same process again.

-1/2+(-2 1/6)= -2 2/3
-2 1/2-(-2 2/3)= 1/6

-1/2+(-1 5/6)= -2 1/3
-2 1/2-(-2 1/3)= -1/6

Now we have one more square to do. But you should always check your answer just in case.

We do the same thing, you could choose which numbers. You could go vertical or horizontal.
I'm going to do both ways to show that it doesn't really matter as long as you get the right answer.
1/6+(-1 1/6)= -1
-2 1/2-(-1)= -1 1/2
OR
-1/6+(-5/6)= -1
-2 1/2-(-1)= -1 1/2

I got the same answer so now we fill in the last square.

And that is how you do question #20!

Thanks for reading! Hope you enjoyed it. If you find a mistake, please comment and I'll fix it.

Mr. B. said...

Zerlina, a little error. Your negative sign in the very first sum is beside your 1/2. I'm thinking it should be in front of the whole number to make it an integer. Fix please. Otherwise thanks for the post!

shaneille 9-05 said...

Great Job Zerlina! That was a hard question, i didn't understand it until now. Sudoku it is like. I like your pictures and you explainions. You made it very clear. Thanks!

Aleiah 905 said...

Good job Zerlina! I thought this question would be really hard but your explanation made it all easy to understand!