I would probably approach it as follows:

use List::Util qw(min);

my @array = 13 .. 234;

for (0 .. $#array/20) {
    my $beg = $_ * 20;
    my $end = min($beg + 19, $#array);

    print for @array[ $beg .. $end ];
    <STDIN> unless $end >= $#array;
}
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