What does $ordnum look like? Does it look like a number or does it contain non-numeric characters? If the latter, you'll want to use a string comparison here:

if ($PARTS eq $ordnum) {
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Also, note that the elements of the @PARTS array will have the terminating newline at the end, and this will interfere with string comparisons. To get rid of that, you can use:

chomp(@PARTS = <PARTS>);
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Frankly, my preference is use a read loop:

while (<PARTS>) {
  chomp;
  if ($_ eq $ordnum) { ...
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And finally, you can make your search a little more efficient by short-circuiting the loop when you've found a match:

for $PARTS (@PARTS) {
  if ($PARTS eq $ordnum) { # assuming 'eq' is correct here
    $found = 1;
    last;
  }
}
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