In[1]:= Partition[
 Table[IntegerDigits[(1010101030 + 100 k)^2][[15]], {k, 1, 50}], 25]

Out[1]=
{{7, 1, 6, 4, 4, 5, 9, 4, 2, 2, 3, 7, 2, 0, 0, 1, 5, 0, 8, 8, 9, 3, 8, 6, 6},
 {7, 1, 6, 4, 4, 5, 9, 4, 2, 2, 3, 7, 2, 0, 0, 1, 5, 0, 8, 8, 9, 3, 8, 6, 6}}

In[2]:= Partition[
 Table[IntegerDigits[(1010101070 + 100 k)^2][[15]], {k, 1, 50}], 25]

Out[2]=
{{6, 1, 7, 6, 6, 8, 3, 9, 8, 8, 0, 5, 1, 0, 0, 2, 7, 3, 2, 2, 4, 9, 5, 4, 4},
 {6, 1, 7, 6, 6, 8, 3, 9, 8, 8, 0, 5, 1, 0, 0, 2, 7, 3, 2, 2, 4, 9, 5, 4, 4}}