My previous answer is wrong, because variables are interpolated at the time the regex is created. This relatively compact expression works, though:

use strict;
use warnings;

my @nums = (100,-3,150,-2,-1,256, 280, 254);;

foreach my $n (@nums)
{
    print "$n: ",
    ($n !~ /^1?\d{1,2}$|^2(?:[0-4]\d|5[0-5])$/)
    ? 'fail' : 'pass';
}
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