diff --git a/01_grundlagen/unterricht/tag04/01_escape-notation.html b/01_grundlagen/unterricht/tag04/01_escape-notation.html
new file mode 100644
index 0000000..000d2da
--- /dev/null
+++ b/01_grundlagen/unterricht/tag04/01_escape-notation.html
@@ -0,0 +1,54 @@
+<!doctype html>
+<html lang="de">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>All Escape Characters</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/7.3.1/css/all.min.css" />
+
+    <style>
+      .list-check {
+        list-style: none;
+        margin: 0;
+        padding: 0 0 0 20px; /* top right bottom left*/
+      }
+
+      .list-check li::before {
+        content: '\f058';
+        font-family: 'Font Awesome 7 Free';
+        font-weight: 900;
+        margin-right: 10px;
+      }
+    </style>
+  </head>
+  <body>
+    <main>
+      <div class="container py-5">
+        <h1><i class="fa-solid fa-bookmark"></i> All Escape Characters</h1>
+        <ul class="list list-check">
+          <li>
+            <a
+              href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Regular_expressions/Character_escape">
+              All Escape Characters
+            </a>
+          </li>
+          <li><a href="../../docs/escape-notation.pdf">Escape Notation PDF</a></li>
+        </ul>
+        <div class="output alert alert-secondary my-3"></div>
+      </div>
+    </main>
+    <script>
+      'use strict';
+
+      const outputEl = document.querySelector('.output');
+
+      const text =
+        'Please enter the number of files for the following directory:\nC:\\important_folder\\next_important_folder';
+
+      console.log(text);
+
+      outputEl.innerHTML = text.replaceAll('\n', '<br />');
+    </script>
+  </body>
+</html>
diff --git a/01_grundlagen/unterricht/tag04/02_implizite-typkonvertierung.html b/01_grundlagen/unterricht/tag04/02_implizite-typkonvertierung.html
new file mode 100644
index 0000000..09c2bf2
--- /dev/null
+++ b/01_grundlagen/unterricht/tag04/02_implizite-typkonvertierung.html
@@ -0,0 +1,52 @@
+<!doctype html>
+<html lang="de">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Implizite Typkonvertierung</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+  </head>
+  <body>
+    <main>
+      <div class="container py-5">
+        <h1>Implizite Typkonvertierung</h1>
+      </div>
+    </main>
+    <script>
+      'use strict';
+
+      console.log('5' * '4'); // => 20
+      console.log('5' * 4); // => 20
+      console.log(5 * '4'); // => 20
+
+      console.log('5' - '4'); // => 1 (Typ: number)
+      console.log('5' - 4); // => 1 (Typ: number)
+      console.log(5 - '4'); // => 1 (Typ: number)
+      console.log('5' / '4'); // => 1.25 (Typ: number)
+      console.log('5' / 4); // => 1.25 (Typ: number)
+      console.log(5 / '4'); // => 1.25 (Typ: number)
+
+      console.log('5' ** '2'); // => 25 (Typ: number)
+
+      // Aufpassen bei + (Verkettung oder Addition)
+      console.log(3 + 4); // => 7 <- 'number'
+      console.log('3' + '4'); // => '34' <- 'string'
+      console.log('3' + 4); // => '34' <- 'string'
+      console.log(3 + '4'); // => '34' <- 'string'
+
+      console.log('5€' - 4); // => NaN - Not a Number <- (Typ: number)
+      console.log('16px' * 2); // => NaN - Not a Number <- (Typ: number)
+      console.log('16 weitere Zeichen auf Ziffern' * 2); // => NaN - Not a Number <- (Typ: number)
+
+      console.log('  45  ' * 2); // => 90 <- (Type: number)
+
+      console.log(typeof NaN); // => 'number'
+
+      // ==========
+      console.log(typeof 'hello' * 4); // => 'string' * 4 -> NaN
+      console.log(typeof 'hello' + 4); // => 'string' + 4 -> 'string4'
+
+      console.log('b' + 'a' + +'a' + 'a'); // => 'baNaNa';
+    </script>
+  </body>
+</html>
diff --git a/01_grundlagen/unterricht/tag04/03_explizite-typkonvertierung.html b/01_grundlagen/unterricht/tag04/03_explizite-typkonvertierung.html
new file mode 100644
index 0000000..b4c9a3b
--- /dev/null
+++ b/01_grundlagen/unterricht/tag04/03_explizite-typkonvertierung.html
@@ -0,0 +1,50 @@
+<!doctype html>
+<html lang="de">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Explizite Typkonvertierung</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+  </head>
+  <body>
+    <main>
+      <div class="container py-5">
+        <h1>Explizite Typkonvertierung</h1>
+        <div class="output alert alert-secondary my-3"></div>
+      </div>
+    </main>
+    <script>
+      'use strict';
+
+      const outputEl = document.querySelector('.output');
+
+      // explizite Typekonvertierung Number('string')
+      const price1 = Number(prompt('Price of article 1?'));
+      const price2 = Number(prompt('Price of article 2?'));
+      const price3 = Number(prompt('Price of article 3?'));
+
+      const result = `total: ${price1 + price2 + price3}`;
+
+      console.log(result);
+      outputEl.textContent = result;
+
+      // ========
+      console.log(Number('    300  ')); // => 300 <- 'number'
+      console.log(Number('hello')); // => NaN <- 'number'
+      console.log(Number('3px')); // => NaN <- 'number'
+
+      console.log(parseInt('3px')); // => 3 <- 'number'
+      console.log(parseInt('3.5rem')); // => 3 <- 'number'
+      console.log(parseFloat('3.5rem')); // => 3.5 <- 'number'
+      console.log(parseFloat('$3.5rem')); // => NaN <- 'number'
+
+      console.log(String(10)); // => '10' <- 'string'
+      console.log((10).toString()); // => '10' <- 'string'
+
+      console.log(Boolean(1)); // => true <- 'boolean'
+      console.log(Boolean(0)); // => false <- 'boolean'
+      console.log(Boolean('')); // => false <- 'boolean'
+      console.log(Boolean('a')); // => true <- 'boolean'
+    </script>
+  </body>
+</html>
diff --git a/01_grundlagen/unterricht/tag04/04_nan-paradoxon.html b/01_grundlagen/unterricht/tag04/04_nan-paradoxon.html
new file mode 100644
index 0000000..ac97c24
--- /dev/null
+++ b/01_grundlagen/unterricht/tag04/04_nan-paradoxon.html
@@ -0,0 +1,29 @@
+<!doctype html>
+<html lang="de">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>NaN - Paradoxon</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+  </head>
+  <body>
+    <main>
+      <div class="container py-5">
+        <h1>NaN - Paradoxon</h1>
+        <p>Die <code>NaN</code> globale Eigenschaft ist ein Wert, der „Nicht eine Zahl“ (Not-a-Number) darstellt.</p>
+      </div>
+    </main>
+    <script>
+      'use strict';
+
+      console.log(Number('NerdWorld')); // =>  NaN
+      console.log(Number('NerdWorld 2')); // =>  NaN
+      console.log('Drei' * 3); // =>  NaN
+      console.log(Number('NerdWorld') * 3); // NaN * 3 =>  NaN
+      console.log(NaN * 3); // =>  NaN
+      console.log(12 / '3Produkte'); // =>  NaN
+      console.log(12 / '3'); // =>  4
+      console.log(12 / Number('3Produkte')); // =>  NaN
+    </script>
+  </body>
+</html>
diff --git a/01_grundlagen/unterricht/tag04/05_math-api.html b/01_grundlagen/unterricht/tag04/05_math-api.html
new file mode 100644
index 0000000..99d72a3
--- /dev/null
+++ b/01_grundlagen/unterricht/tag04/05_math-api.html
@@ -0,0 +1,176 @@
+<!doctype html>
+<html lang="de">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Math Object in JS</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+  </head>
+  <body>
+    <main>
+      <div class="container py-5">
+        <h1>Math Object in JS</h1>
+        <p>
+          Math ist ein Standardobjekt, das Eigenschaften und Methoden für mathematische Konstanten und Funktionen
+          besitzt.
+        </p>
+        <ul class="list">
+          <li>
+            <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math">
+              Das Math Objekt
+            </a>
+          </li>
+        </ul>
+        <!-- table.table.table-striped.my-3>thead.table-dark>tr>th{Methode oder Konstante}+th{Zweck}+th{Beispiel} -->
+        <table class="table table-striped my-3">
+          <thead class="table-dark">
+            <tr>
+              <th>Methode oder Konstante</th>
+              <th>Zweck</th>
+              <th>Beispiel</th>
+            </tr>
+          </thead>
+          <!-- tbody>tr*11>td*3  -->
+          <tbody>
+            <tr>
+              <td>
+                <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/sqrt">
+                  sqrt
+                </a>
+              </td>
+              <td>Quadratwurzel</td>
+              <td>Math.sqrt(9) ergibt 3/td></td>
+            </tr>
+            <tr>
+              <td>
+                <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/pow">
+                  pow
+                </a>
+              </td>
+              <td>Potenzieren</td>
+              <td>Math.pow(2, 5) ergibt 32</td>
+            </tr>
+            <tr>
+              <td>
+                <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/cos">
+                  cos
+                </a>
+              </td>
+              <td>Kosinus</td>
+              <td>Math.cos(0) ergibt 1</td>
+            </tr>
+            <tr>
+              <td>
+                <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/pi">PI</a>
+              </td>
+              <td>π</td>
+              <td>Math.PI ergibt 3.141592653589793</td>
+            </tr>
+            <tr>
+              <td>
+                <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/round">
+                  round
+                </a>
+              </td>
+              <td>kaufmännisches Runden</td>
+              <td>Math.round(3.678) ergibt 4</td>
+            </tr>
+            <tr>
+              <td>
+                <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/floor">
+                  floor
+                </a>
+              </td>
+              <td>Abrunden</td>
+              <td>Math.floor(3.678) ergibt 3</td>
+            </tr>
+            <tr>
+              <td>
+                <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/ceil">
+                  ceil
+                </a>
+              </td>
+              <td>Aufrunden</td>
+              <td>Math.ceil(3.678) ergibt 4</td>
+            </tr>
+            <tr>
+              <td>
+                <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/max">
+                  max
+                </a>
+              </td>
+              <td>Maximalwert aus beliebig vielen Argumenten</td>
+              <td>Math.max(3, 7, 2) ergibt 7</td>
+            </tr>
+            <tr>
+              <td>
+                <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/min">
+                  min
+                </a>
+              </td>
+              <td>Minimalwert aus beliebig vielen Argumenten</td>
+              <td>Math.min(3, 7, 2) ergibt 2</td>
+            </tr>
+            <tr>
+              <td>
+                <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/abs">
+                  abs
+                </a>
+              </td>
+              <td>Betrag einer Zahl (ohne Vorzeichen)</td>
+              <td>Math.abs(-3.678) ergibt 3.678</td>
+            </tr>
+            <tr>
+              <td>
+                <a href="https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/random">
+                  random
+                </a>
+              </td>
+              <td>Eine zufällige Zahl</td>
+              <td>Math.random() gibt eine zufällige Zahl zwischen 0 und 1 zurück, wobei die 1 nie erreicht wird</td>
+            </tr>
+          </tbody>
+        </table>
+      </div>
+    </main>
+    <script>
+      'use strict';
+
+      console.log(Math.sqrt(9)); // => 3 Quadratwurzel
+
+      console.log(Math.pow(2, 5)); // => 2^5 = 2 * 2 * 2 * 2 * 2 => 32
+      console.log(2 ** 5); // => 2^5 = 2 * 2 * 2 * 2 * 2 => 32
+
+      console.log(Math.cos(0)); // => 1
+      console.log(Math.sin(1)); // => 0.8414709848078965
+
+      console.log(Math.max(3, 7, 20, 1)); //=> 20
+
+      const numbers = [3, 7, 20, 1];
+      console.log(numbers[0]); // => 3
+      console.log(numbers[1]); // => 7
+
+      console.log(Math.max(...numbers)); // => 20
+
+      console.log(Math.min(3, 7, 20, 1)); //=> 1
+
+      console.log(Math.abs(-3)); // => 3
+
+      console.log(Math.round(3.1)); // => 3
+      console.log(Math.round(3.5)); // => 4
+      console.log(Math.round(3.4999999999)); // => 3
+
+      console.log(Math.floor(3.9)); // => 3
+      console.log(Math.floor(3.1)); // => 3
+
+      console.log(Math.ceil(3.9)); // => 4
+      console.log(Math.ceil(3.1)); // => 4
+      console.log(Math.ceil(3.01)); // => 4
+
+      // =========
+      console.log(Math.random()); //=> Zufallszahl zwischen 0 und 1
+
+      console.log(Math.floor(Math.random() * 6) + 1); // Würfelwurf
+    </script>
+  </body>
+</html>
diff --git a/01_grundlagen/unterricht/tag04/06_number-to-fixed.html b/01_grundlagen/unterricht/tag04/06_number-to-fixed.html
new file mode 100644
index 0000000..35286db
--- /dev/null
+++ b/01_grundlagen/unterricht/tag04/06_number-to-fixed.html
@@ -0,0 +1,45 @@
+<!doctype html>
+<html lang="de">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Number.toFixed()</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+  </head>
+  <body>
+    <main>
+      <div class="container py-5">
+        <h1>Number.toFixed()</h1>
+        <p>Die <strong>toFixed()</strong> - Methode formatiert eine Zahl inf Festkommadarstellung</p>
+
+        <div class="alert alert-danger">
+          <p><strong>Achtung:</strong> Rückgabewert ist ein String-Objekt der gegebenen Zahl in Festkommadarstellung</p>
+        </div>
+
+        <ul class="list">
+          <li>
+            <a
+              href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toFixed?retiredLocale=de">
+              Number.toFixed()
+            </a>
+          </li>
+        </ul>
+      </div>
+    </main>
+    <script>
+      'use strict';
+
+      const zahl = 3.4576321;
+      const zahl2 = 10;
+
+      console.log(zahl.toFixed(3)); // => '3.458' <- 'string'
+      // ACHTUNG
+      console.log(zahl.toFixed(2) + 10); // => '3.4610' <- 'string' // ACHTUNG VERKETTUNG FINDET STATT
+
+      console.log(Number(zahl.toFixed(2)) + 10); // => 13.46 <- 'number'
+
+      console.log(zahl2.toFixed(2)); // => '10.00';
+      console.log((10).toFixed(2)); // => '10.00';
+    </script>
+  </body>
+</html>