Question

complete the magic square given below, so that the sum of the numbers in each row or in each column or along each diagonal is 15.

6	1
	5

Answer 1

Taking the diagonal that starts with 6:
$6+5+x=15\Rightarrow x=4$

6	1
	5
		4

Now, taking the first row:
$6+1+x=15\Rightarrow x=8$

6	1	8
	5
		4

Taking the last column:
$8+x+4=15\Rightarrow x=3$

6	1	8
	5	3
		4

Taking the second column:
$1+5+x=15\Rightarrow x=9$

6	1	8
	5	3
	9	4

Taking the second row:
$x+5+3=15\Rightarrow x=7$

6	1	8
7	5	3
	9	4

Taking the diagonal that begins with 8:
$8+5+x=15\Rightarrow x=2$

6	1	8
7	5	3
2	9	4