Question

The numbers in each row or column of the square are written according to the same rule By identifying the rule, find the missing number.

5	8	7
11	17	15
21	33	?

Answer 1

This magic square is not the usual magic square, Here each column is a sequence.
5 x 2 + 11 = 21
8 x 2 + 17 = 33
So logically the answer is 7 x 2 + 15 = 29.
You may also look at the sequence like :
5 x 2 + 1 = 11
5 x 4 + 1 = 21
8 x 2 + 1 = 17
8 x 4 + 1 = 33
7 x 2 + 1 = 15
Therefore, 7 x 4 + 1 = missing number = 29.