As always, there is more than one way to do it. For each of the examples below, assume the following setup:

my $string = "1234567890abcdefghijABCDEFGHIJK";
my $chars;
my $n = 2;
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With substr:

$chars = substr( $string, 0, $n );
substr( $string, 0, $n ) = "";
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Another with substr:

( $chars, $string ) = ( substr($string,0,$n), substr($string,$n) );
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And probaby the best substr solution:

$chars = substr ($string, 0, $n, "");
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With a substitution s/// regexp:

$string = s/^(.{$n})(.*)$/$2/s;
$chars = $1;
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With split:

($chars, $string) = split /^(.{$n})/, $string, 1;
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With a pattern match (m//):

($chars, $string) = $string =~ /^(.{$n})(.*)$/s;
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With unpack (Not for the faint of heart):

( $chars, $string ) = unpack "a$n a@{[length($string)-$n]}", $string;
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