openfreebooks-bookgenerator/content/math/zero-and-one/supplement.html

<div class="book-prose">
  <h2 id="history" class="book-prose__heading">History</h2>
  <p>
    People counted with fingers and marks long before anyone wrote <strong>0</strong> as a number.
    In ancient India and among the Maya, thinkers found a symbol for <strong>nothing</strong> — not
    just “empty space on the page,” but a number you could calculate with.
  </p>
  <p>
    That step mattered: without zero, place value and modern arithmetic are much harder. The idea
    “nothing is something we can name” is as deep as the idea “one is one.”
  </p>

  <h2 id="checkpoints" class="book-prose__heading">Checkpoints</h2>
  <details class="book-question">
    <summary class="book-question__prompt">You look in a box and see no dots. How many?</summary>
    <div class="book-question__solution">
      <p><strong>Answer:</strong> \(0\) (zero) — nothing to count.</p>
    </div>
  </details>
  <details class="book-question">
    <summary class="book-question__prompt">You see exactly one dot. How many?</summary>
    <div class="book-question__solution">
      <p><strong>Answer:</strong> \(1\) (one).</p>
    </div>
  </details>
  <details class="book-question">
    <summary class="book-question__prompt">Is the sentence “2 is less than 1” true or false?</summary>
    <div class="book-question__solution">
      <p><strong>Answer:</strong> False — two is not less than one.</p>
    </div>
  </details>

  <h2 id="references" class="book-prose__heading">References</h2>
  <ul>
    <li>Ifrah, Georges — <em>The Universal History of Numbers</em> (origins of zero and counting).</li>
    <li>Crossley &amp; Henry — early Indian arithmetic including zero.</li>
  </ul>
</div>