36...49....64...81...100...121...144
They are the square numbers.
The next number is -21
50
7
36
This is the series of square numbers, (16= 4*4). The next number is 5*5=25.
If you mean: 1 4 9 16 25 then it is 36
The next number is -21
49
50
7
32
49
the answer will be 21
36
10
225
26