Using regular expressions.

$str="art1532";
($a, $b)=$str=~/([a-zA-Z]+)(\d+)/;
print "$a --- $b\n";
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The first part consist of a-z, A-Z (at least one letter), if you use "+". Or you can use "*", then it could happen that there are no letters before a number. After letters we should find digits (at least one digit). We save what we found in $a and $b. Print the result. Done. You can find additional information on regular expressions at http://www.perlmonks.com/index.pl?node=Tutorials.