Challenge 1: Count Vowels with the Count Idiom — Possible Solution
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use strict;
use warnings;
use feature 'say';

my $word = "encyclopedia";

my $vowel_count = () = $word =~ /[aeiou]/g;
say $vowel_count;

Output:
5

WHY THIS WORKS AS AN ANSWER
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$word =~ /[aeiou]/g reuses a plain character-class regex (Course 1,
Chapter 6) matching any single vowel, combined with the /g modifier
so every occurrence in the string is found, not just the first.

my $vowel_count = () = ... reuses the chapter's own count idiom
exactly, unchanged in structure — only the regex differs from the
chapter's own /ERROR/g example. The =~ match runs in LIST context
first (forced by assigning to the empty (), per the chapter's own
explanation), returning every matched vowel character as a list; that
list is then assigned to $vowel_count in SCALAR context, which
evaluates to how many elements were in it.

"encyclopedia" spelled out is e-n-c-y-c-l-o-p-e-d-i-a. Checking each
letter against [aeiou] (note: y is NOT included in this character
class, so it doesn't count as a vowel here) gives five matches: the
e at position 1, the o at position 7, the e at position 9, the i at
position 11, and the a at position 12 — five vowels total, matching
the printed output.