See pack, unpack and perlpacktut:

>perl -wMstrict -le
"my $raw = pack 'H*', '8447000c0000110a0350350400640a';
 my ($n) = unpack 'x v', $raw;
 print $n;
"
71
[download]

Update: If  $n is the count of a number of items that follow it, see the '/' unpack template specifier:

>perl -wMstrict -le
"my $raw = pack 'H*', '8407000c0b0a09080706';
 my @chars = unpack 'x v/C', $raw;
 print qq{@chars};
"
12 11 10 9 8 7 6
[download]