diff --git a/src/04-collections/KATA/solution.ts b/src/04-collections/KATA/solution.ts
new file mode 100644
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+++ b/src/04-collections/KATA/solution.ts
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+// 1. Arrays: Implementiere die folgenden Funktionen
+export function squareNumbers(numbers: number[]): number[] {
+  return numbers.map((num) => num * num);
+}
+
+export function filterEvenNumbers(numbers: number[]): number[] {
+  return numbers.filter((num) => num % 2 === 0);
+}
+
+export function sumNumbers(numbers: number[]): number {
+  return numbers.reduce((acc, num) => acc + num, 0);
+}
+
+export function findFirstGreaterThan(
+  numbers: number[],
+  limit: number
+): number | undefined {
+  return numbers.find((num) => num > limit);
+}
+
+export function sortNumbersDescending(numbers: number[]): number[] {
+  return [...numbers].sort((a, b) => b - a);
+}
+
+export function sliceNumbers(
+  numbers: number[],
+  start: number,
+  end: number
+): number[] {
+  return numbers.slice(start, end);
+}
+
+export function modifyArray(
+  numbers: number[],
+  index: number,
+  newValue: number
+): number[] {
+  const modified = [...numbers];
+  modified.splice(index, 1, newValue);
+  return modified;
+}
+
+// 2. Maps: Implementiere die folgenden Funktionen
+export function createUserMap(): Map<number, string> {
+  return new Map([
+    [1, 'Alice'],
+    [2, 'Bob'],
+  ]);
+}
+
+export function getUserById(
+  users: Map<number, string>,
+  id: number
+): string | undefined {
+  return users.get(id);
+}
+
+export function getAllUserIds(users: Map<number, string>): number[] {
+  return Array.from(users.keys());
+}
+
+export function getAllUserNames(users: Map<number, string>): string[] {
+  return Array.from(users.values());
+}
+
+// 3. Sets: Implementiere die folgenden Funktionen
+export function createUniqueNumberSet(numbers: number[]): Set<number> {
+  return new Set(numbers);
+}
+
+export function isNumberInSet(set: Set<number>, value: number): boolean {
+  return set.has(value);
+}
+
+export function convertSetToArray(set: Set<number>): number[] {
+  return Array.from(set);
+}
diff --git a/src/04-collections/collection-methods.ts b/src/04-collections/collection-methods.ts
new file mode 100644
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+++ b/src/04-collections/collection-methods.ts
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+// 1. Arrays verarbeiten
+const numbers = [1, 2, 3, 4, 5];
+
+// Map: Elemente quadrieren
+const squared = numbers.map((num) => num * num);
+console.log(squared); // [1, 4, 9, 16, 25]
+
+// Filter: Nur gerade Zahlen behalten
+const evens = numbers.filter((num) => num % 2 === 0);
+console.log(evens); // [2, 4]
+
+// Reduce: Alle Werte summieren
+const sum = numbers.reduce((acc, num) => acc + num, 0);
+console.log(sum); // 15
+
+// Includes: Prüfen, ob ein Wert enthalten ist
+console.log(numbers.includes(3)); // true
+
+// Find: Erstes Element, das einer Bedingung entspricht
+const found = numbers.find((num) => num > 3);
+console.log(found); // 4
+
+// Some: Prüfen, ob mindestens ein Element die Bedingung erfüllt
+const hasEven = numbers.some((num) => num % 2 === 0);
+console.log(hasEven); // true
+
+// Every: Prüfen, ob alle Elemente die Bedingung erfüllen
+const allPositive = numbers.every((num) => num > 0);
+console.log(allPositive); // true
+
+// Sort: Array sortieren
+const sortedNumbers = [...numbers].sort((a, b) => b - a);
+console.log(sortedNumbers); // [5, 4, 3, 2, 1]
+
+// Slice: Ein Teil des Arrays extrahieren
+const sliced = numbers.slice(1, 3);
+console.log(sliced); // [2, 3]
+
+// Splice: Elemente aus dem Array entfernen oder ersetzen
+const modifiedNumbers = [...numbers];
+modifiedNumbers.splice(2, 1, 99); // Entfernt das dritte Element und fügt 99 ein
+console.log(modifiedNumbers); // [1, 2, 99, 4, 5]
+
+// 2. Maps verarbeiten
+const userMap = new Map<number, string>();
+userMap.set(1, 'Alice');
+userMap.set(2, 'Bob');
+
+// Alle Einträge ausgeben
+userMap.forEach((name, id) => console.log(`${id}: ${name}`));
+
+// Alle Schlüssel als Array speichern
+const ids = Array.from(userMap.keys());
+console.log(ids); // [1, 2]
+
+// Alle Werte als Array speichern
+const names = Array.from(userMap.values());
+console.log(names); // ["Alice", "Bob"]
+
+// 3. Sets verarbeiten
+const uniqueNumbers = new Set([1, 2, 3, 4, 5, 2, 3]);
+console.log(uniqueNumbers); // Set(5) {1, 2, 3, 4, 5}
+
+// Prüfen, ob eine Zahl existiert
+console.log(uniqueNumbers.has(3)); // true
+
+// Set in ein Array umwandeln
+const numArray = Array.from(uniqueNumbers);
+console.log(numArray); // [1, 2, 3, 4, 5]