##OUTPUT##
Argument "1.gb.txt" isn't numeric in numeric comparison (<=>) at SortQuestion.pl line 11, <DATA> line 9.
...
...
sequence1.gb.txt
sequence2.gb.txt
sequence3.gb.txt
sequence4.gb.txt
sequence5.gb.txt
sequence7.gb.txt
sequence8.gb.txt
sequence9.gb.txt