I know you can do it with a regular-expression. I'm not sure if you can with a regular split.

my $s='4sheet1rev11';
while($s=~/([\d]+|[^\d]+)/gcsi){
  print "$1\n";
}
[download]

Just saw the other comments. It can be done w/ split.

That's what I love about perl... there are always many ways to solve any problem and I'm always learning something new.