Square root of 123,456,789
=111,111,111
111,111,111 - 123,456,789
=12,345,678

Square root of 12,345,678
=11,111,111
11,111,111 - 12,345,678
=1,234,567

Square root of 1,234,567
=1,111,111
1,111,111 - 1,234,567
=123,456

Square root of 123,456
=111,111
111,111 - 123,456
=12,345

Square root of 12,345
=11,111
11,111 - 12,345
=1,234

Square root of 1,234
=1,111
1,111 - 1,234
=123

Square root of 123
=111
111 - 123
=12

1 - 2 = -1