What value completes the square for the expression x^2+16x 64 8 -64 -8

You have the expression x^2+16x. Then, to find the value that completes the square for it, you must apply the following proccedure:
 
 x^2+16x=0
 x^2+16x+0=0
 
 This quadratic equation needs to have the following form:
 
 a(x+d)^2+e
 
 Then, you have:
 
 (b/2)^2=(16/2)^2=(8)^2=64
 
 Therefore, the expression is:
 
 x^2+16x+64=64
 (x+8)^2=64
 
 The answer is the first option= 64