$ perl -E 'say for sort qw{1.X 9.X}'
1.X
9.X

$ perl -E 'say for sort qw{1.X 9.X 10.X}'
1.X
10.X
9.X

$ perl -E 'say for sort qw{01.X 09.X 10.X}'
01.X
09.X
10.X