Challenge 1: LibreOffice Writer's Default Save Format — Solution Walkthrough

Steps:
  1. Open LibreOffice Writer, start a new blank document.
  2. File > Save (or Ctrl+S), give it a filename, confirm the save.

Which extension LibreOffice chooses by default:

.odt (Open Document Text) — LibreOffice Writer's own native format.

Why this specific extension:

ODF (Open Document Format) is LibreOffice's own native file format —
.odt for Writer specifically, the same family as .ods (Calc) and .odp
(Impress). Since this is a brand-new document created directly in
Writer, with no existing Microsoft-format file already open, there's
nothing prompting LibreOffice to consider any other format at all —
it simply defaults to its own native one, exactly the way Microsoft
Word would default to .docx for a brand-new document with no prior
format context to inherit from.

Notes:
- This default only changes if you explicitly pick a different file
  type in the Save dialog's own format dropdown, or if the document
  was originally opened FROM an existing Microsoft-format file (as in
  Exercise 2) rather than created fresh.