Answer
34
Work Step by Step
The digits of each row, column and diagonal add to the sum of 34, making this a magic square.
Row 1: $16+3+2+13=34$
Row 2: $5+10+11+8=34$
Row 3: $9+6+7+12=34$
Row 4: $4+15+14+1=34$
Column A: $16+5+9+4=34$
Column B: $3+10+6+15=34$
Column C: $2+11+7+14=34$
Column D: $13+8+12+1=34$
Upper left to lower right: $16+10+7+1=34$
Lower left to upper right: $4+6+11+13=34$
