Explanation:

series  4,16,6,36,8,64,10,()
 
 4^2=16
 1st number square 16
 4+2=6
 added 2 to 1st number
 6^2=36
 3rd number square is 36
 6+2=8
 added 2 
 8^2=64
 fifth number square is 64
 8+2=10
 added 2
 10^2=100
 7 th term square 100
 100 is filled in the series