diff --git a/codewars/Adding Big Numbers/Adding Big Numbers.js b/codewars/Adding Big Numbers/Adding Big Numbers.js
new file mode 100644
index 000000000..5cac82529
--- /dev/null
+++ b/codewars/Adding Big Numbers/Adding Big Numbers.js	
@@ -0,0 +1,19 @@
+function add(num1, num2) {
+    let result = '';
+    let carry = 0;
+    let i = num1.length - 1;
+    let j = num2.length - 1;
+    while (i >= 0 || j >= 0 || carry > 0) {
+        const digit1 = i >= 0 ? parseInt(num1[i]) : 0; 
+        const digit2 = j >= 0 ? parseInt(num2[j]) : 0;
+
+        const sum = digit1 + digit2 + carry;
+        result = (sum % 10) + result;
+        carry = Math.floor(sum / 10);
+
+        i--;
+        j--;
+    }
+
+    return result;
+}
\ No newline at end of file
diff --git a/codewars/Anagram difference/Anagram defferende.js b/codewars/Anagram difference/Anagram defferende.js
new file mode 100644
index 000000000..9acb59fb8
--- /dev/null
+++ b/codewars/Anagram difference/Anagram defferende.js	
@@ -0,0 +1,28 @@
+function anagramDifference(w1, w2) {
+    const letters1 = {};
+    const letters2 = {};
+  
+    for (let i = 0; i < w1.length; i++) {
+      const letter = w1[i];
+      letters1[letter] = (letters1[letter] || 0) + 1;
+    }
+  
+    for (let i = 0; i < w2.length; i++) {
+      const letter = w2[i];
+      letters2[letter] = (letters2[letter] || 0) + 1;
+    }
+  
+    let difference = 0;
+    for (const letter in letters1) {
+      difference += Math.abs((letters1[letter] || 0) - (letters2[letter] || 0));
+    }
+    for (const letter in letters2) {
+      if (!(letter in letters1)) {
+        difference += letters2[letter];
+      }
+    }
+  
+    return difference;
+  }
+  
+  
\ No newline at end of file
diff --git a/codewars/Array Deep Count/Array Deep Count.js b/codewars/Array Deep Count/Array Deep Count.js
new file mode 100644
index 000000000..5f70ed309
--- /dev/null
+++ b/codewars/Array Deep Count/Array Deep Count.js	
@@ -0,0 +1,16 @@
+const chai = require("chai");
+const assert = chai.assert;
+chai.config.truncateThreshold = 0;
+
+function deepCount(arr) {
+    let count = 0;
+
+    for (const element of arr) {
+        count++;
+        if (Array.isArray(element)) {
+            count += deepCount(element);
+        }
+    }
+
+    return count;
+}
diff --git a/codewars/Build Tower/Build Tower.js b/codewars/Build Tower/Build Tower.js
new file mode 100644
index 000000000..9508cbfc0
--- /dev/null
+++ b/codewars/Build Tower/Build Tower.js	
@@ -0,0 +1,19 @@
+function towerBuilder(nFloors) {
+    const tower = [];
+    for (let i = 0; i < nFloors; i++) {
+      const stars = (i * 2) + 1; // Количество звездочек на каждой строке
+      const spaces = nFloors - i - 1; // Количество пробелов по краям
+      let row = "";
+      for (let j = 0; j < spaces; j++) {
+        row += " ";
+      }
+      for (let j = 0; j < stars; j++) {
+        row += "*";
+      }
+      for (let j = 0; j < spaces; j++) {
+        row += " ";
+      }
+      tower.push(row);
+    }
+    return tower;
+  }
\ No newline at end of file
diff --git a/codewars/Convert string to camel case/Convert string to camel case.js b/codewars/Convert string to camel case/Convert string to camel case.js
new file mode 100644
index 000000000..8e82f42a3
--- /dev/null
+++ b/codewars/Convert string to camel case/Convert string to camel case.js	
@@ -0,0 +1,16 @@
+function toCamelCase(str) {
+    if (!str) {
+      return "";
+    }
+  
+    const words = str.split(/[-_]/);
+    const camelCaseWords = words.map((word, index) => {
+      if (index === 0) {
+        return word; 
+      } else {
+        return word[0].toUpperCase() + word.slice(1).toLowerCase();
+      }
+    });
+  
+    return camelCaseWords.join("");
+  }
\ No newline at end of file
diff --git a/codewars/Duplicate Encoder/Duplicate Encoder.js b/codewars/Duplicate Encoder/Duplicate Encoder.js
new file mode 100644
index 000000000..e41718174
--- /dev/null
+++ b/codewars/Duplicate Encoder/Duplicate Encoder.js	
@@ -0,0 +1,16 @@
+function duplicateEncode(word)   {
+    const lowerWord = word.toLowerCase();
+    const charCount = {};
+    let result = '';
+
+    for (const char of lowerWord) {
+        charCount[char] = (charCount[char] || 0) + 1;
+    }
+
+    for (const char of lowerWord) {
+        result += charCount[char] === 1 ? '(' : ')';
+    
+
+    }
+
+}
\ No newline at end of file
diff --git a/codewars/Find the missing letter/Find the missing letter.js b/codewars/Find the missing letter/Find the missing letter.js
new file mode 100644
index 000000000..308e8f784
--- /dev/null
+++ b/codewars/Find the missing letter/Find the missing letter.js	
@@ -0,0 +1,27 @@
+function findMissingLetter(array) {
+    2
+      let startLetter = array[0].charCodeAt(0);
+    3
+      let missingLetter = "";
+    4
+    ​
+    5
+      for (let i = 1; i < array.length; i++) {
+    6
+        let currentLetter = array[i].charCodeAt(0);
+    7
+        if (currentLetter - startLetter !== i) {
+    8
+          missingLetter = String.fromCharCode(startLetter + i);
+    9
+          break;
+    10
+        }
+    11
+      }
+    12
+    ​
+    13
+      return missingLetter;
+    14
+    }
\ No newline at end of file
diff --git a/codewars/Flatten a Nested Map/Flatten a Nested Map.js b/codewars/Flatten a Nested Map/Flatten a Nested Map.js
new file mode 100644
index 000000000..e5dd05814
--- /dev/null
+++ b/codewars/Flatten a Nested Map/Flatten a Nested Map.js	
@@ -0,0 +1,14 @@
+function flattenMap(obj, parentKey = '', result = {}) {
+    for (const key in obj) {
+        if (obj.hasOwnProperty(key)) {
+            const newKey = parentKey ? `${parentKey}/${key}` : key; 
+            const value = obj[key];
+            if (typeof value === 'object' && value !== null && !Array.isArray(value)) {
+                flattenMap(value, newKey, result);
+            } else {
+                result[newKey] = value;
+            }
+        }
+    }
+    return result;
+}
diff --git a/codewars/Fun with tree - max sum/Fun with tree - max sum.js b/codewars/Fun with tree - max sum/Fun with tree - max sum.js
new file mode 100644
index 000000000..e69de29bb
diff --git a/codewars/Linked Lists - Sorted Insert/Linked Lists - Sorted Insert.js b/codewars/Linked Lists - Sorted Insert/Linked Lists - Sorted Insert.js
new file mode 100644
index 000000000..effb19442
--- /dev/null
+++ b/codewars/Linked Lists - Sorted Insert/Linked Lists - Sorted Insert.js	
@@ -0,0 +1,26 @@
+function Node(data) {
+    this.data = data;
+    this.next = null;
+  }
+  
+  function sortedInsert(head, data) {
+    const newNode = new Node(data);
+  
+    if (head === null || data < head.data) {
+      newNode.next = head;
+      return newNode;
+    }
+  
+    let current = head;
+    let previous = null;
+  
+    while (current !== null && data >= current.data) {
+      previous = current;
+      current = current.next;
+    }
+  
+    newNode.next = previous.next;
+    previous.next = newNode;
+  
+    return head;
+  }
\ No newline at end of file
diff --git a/codewars/Merge two arrays/Merge two arrays.js b/codewars/Merge two arrays/Merge two arrays.js
new file mode 100644
index 000000000..91c709ced
--- /dev/null
+++ b/codewars/Merge two arrays/Merge two arrays.js	
@@ -0,0 +1,18 @@
+function mergeArrays(chars, nums) {
+    let merged = [];
+    let i = 0;
+    let j = 0;
+  
+    while (i < chars.length || j < nums.length) {
+      if (i < chars.length) {
+        merged.push(chars[i]);
+        i++;
+      }
+      if (j < nums.length) {
+        merged.push(nums[j]);
+        j++;
+      }
+    }
+  
+    return merged;
+  }
\ No newline at end of file
diff --git a/codewars/Moving Zeros To The End/Moving Zeros To The End.js b/codewars/Moving Zeros To The End/Moving Zeros To The End.js
new file mode 100644
index 000000000..e27a0e528
--- /dev/null
+++ b/codewars/Moving Zeros To The End/Moving Zeros To The End.js	
@@ -0,0 +1,18 @@
+function moveZeros(arr) {
+    const result = [];
+    let zeroCount = 0;
+
+    for (const element of arr) {
+        if (element === 0) {
+            zeroCount++;
+        } else {
+            result.push(element);
+        }
+    }
+
+    for (let i = 0; i < zeroCount; i++) {
+        result.push(0);
+    }
+
+    return result;
+}
\ No newline at end of file
diff --git a/codewars/Permutations/Permutations.js b/codewars/Permutations/Permutations.js
new file mode 100644
index 000000000..38472770b
--- /dev/null
+++ b/codewars/Permutations/Permutations.js
@@ -0,0 +1,19 @@
+function permutations(string) {
+    const result = new Set();
+
+    function backtrack(path, remaining) {
+        if (remaining.length === 0) {
+            result.add(path);
+            return;
+        }
+        for (let i = 0; i < remaining.length; i++) {
+            const nextPath = path + remaining[i];
+            const nextRemaining = remaining.slice(0, i) + remaining.slice(i + 1);
+            backtrack(nextPath, nextRemaining);
+        }
+    }
+
+    backtrack('', string);
+    return Array.from(result);
+ 
+}
diff --git a/codewars/Product of consecutive Fib numbers/Product of consecutive Fib numbers.js b/codewars/Product of consecutive Fib numbers/Product of consecutive Fib numbers.js
new file mode 100644
index 000000000..b5ddca63e
--- /dev/null
+++ b/codewars/Product of consecutive Fib numbers/Product of consecutive Fib numbers.js	
@@ -0,0 +1,10 @@
+function productFib(prod) {
+    let a = 0;
+    let b = 1;
+  
+    while (a * b < prod) {
+      [a, b] = [b, a + b];
+    }
+  
+    return [a, b, a * b === prod];
+  }
\ No newline at end of file
diff --git a/codewars/Simple Pig Latin/Simple Pig Latin.js b/codewars/Simple Pig Latin/Simple Pig Latin.js
new file mode 100644
index 000000000..3a6afa1aa
--- /dev/null
+++ b/codewars/Simple Pig Latin/Simple Pig Latin.js	
@@ -0,0 +1,12 @@
+function pigIt(str) {
+    return str
+      .split(' ')
+      .map((word) => {
+        if (word.match(/^[a-zA-Z]+$/)) {
+          return word.slice(1) + word[0] + 'ay'; 
+        } else {
+          return word; 
+        }
+      })
+      .join(' ');
+  }
\ No newline at end of file
diff --git a/codewars/Snail/Snail.js b/codewars/Snail/Snail.js
new file mode 100644
index 000000000..bdc50fd66
--- /dev/null
+++ b/codewars/Snail/Snail.js
@@ -0,0 +1,43 @@
+snail = function(array) {
+    if (array.length === 0 || array[0].length === 0) {
+        return [];
+    }
+
+    const result = [];
+    let top = 0;
+    let bottom = array.length - 1;
+    let left = 0;
+    let right = array[0].length - 1;
+
+    while (top <= bottom && left <= right) {
+       
+        for (let i = left; i <= right; i++) {
+            result.push(array[top][i]);
+        }
+        top++;
+
+       
+        for (let i = top; i <= bottom; i++) {
+            result.push(array[i][right]);
+        }
+        right--;
+
+        if (top <= bottom) {
+           
+            for (let i = right; i >= left; i--) {
+                result.push(array[bottom][i]);
+            }
+            bottom--;
+        }
+
+        if (left <= right) {
+           
+            for (let i = bottom; i >= top; i--) {
+                result.push(array[i][left]);
+            }
+            left++;
+        }
+    }
+
+    return result;
+};
\ No newline at end of file
diff --git a/codewars/Sum of Digits - Digital Root/Sum of Digits - Digital Root.js b/codewars/Sum of Digits - Digital Root/Sum of Digits - Digital Root.js
new file mode 100644
index 000000000..5419f64d5
--- /dev/null
+++ b/codewars/Sum of Digits - Digital Root/Sum of Digits - Digital Root.js	
@@ -0,0 +1,13 @@
+function digitalRoot(n) {
+    if (n < 10) {
+      return n;
+    }
+  
+    let sum = 0;
+    while (n > 0) {
+      sum += n % 10;
+      n = Math.floor(n / 10);
+    }
+  
+    return digitalRoot(sum);
+  }
\ No newline at end of file
diff --git a/codewars/Sum of Intervals/Sum of Intervals.js b/codewars/Sum of Intervals/Sum of Intervals.js
new file mode 100644
index 000000000..e69de29bb
diff --git a/codewars/Tic-Tac-Toe Checker/Tic-Tac-Toe Cheacker.js b/codewars/Tic-Tac-Toe Checker/Tic-Tac-Toe Cheacker.js
new file mode 100644
index 000000000..37994ce12
--- /dev/null
+++ b/codewars/Tic-Tac-Toe Checker/Tic-Tac-Toe Cheacker.js	
@@ -0,0 +1,34 @@
+function isSolved(board) {
+    function checkWinner(player) {
+      for (let i = 0; i < 3; i++) {
+        if (board[i][0] === player && board[i][1] === player && board[i][2] === player) {
+          return true;
+        }
+      }
+      for (let i = 0; i < 3; i++) {
+        if (board[0][i] === player && board[1][i] === player && board[2][i] === player) {
+          return true;
+        }
+      }
+      if (board[0][0] === player && board[1][1] === player && board[2][2] === player) {
+        return true;
+      }
+      if (board[0][2] === player && board[1][1] === player && board[2][0] === player) {
+        return true;
+      }
+      return false;
+    }
+  
+    if (checkWinner(1)) return 1; // Игрок 1 победил
+    if (checkWinner(2)) return 2; // Игрок 2 победил
+  
+    for (let row of board) {
+      for (let cell of row) {
+        if (cell === 0) {
+          return -1; // Игра продолжается
+        }
+      }
+    }
+  
+    return 0; // Ничья
+  }
\ No newline at end of file
diff --git a/codewars/Valid Parentheses/Valid Parentheses.js b/codewars/Valid Parentheses/Valid Parentheses.js
new file mode 100644
index 000000000..551dbf599
--- /dev/null
+++ b/codewars/Valid Parentheses/Valid Parentheses.js	
@@ -0,0 +1,17 @@
+function validParentheses(s) {
+    let balance = 0;
+
+    for (let char of s) {
+        if (char === '(') {
+            balance++;
+        } else if (char === ')') {
+            balance--;
+        }
+
+        if (balance < 0) {
+            return false;
+        }
+    }
+
+    return balance === 0;
+}
diff --git a/codewars/Where my anagrams at/Where my anagrams at.js b/codewars/Where my anagrams at/Where my anagrams at.js
new file mode 100644
index 000000000..c8f65b8b1
--- /dev/null
+++ b/codewars/Where my anagrams at/Where my anagrams at.js	
@@ -0,0 +1,4 @@
+function anagrams(word, words) {
+    const sortedWord = word.split('').sort().join('');
+    return words.filter(w => w.split('').sort().join('') === sortedWord);
+  }
\ No newline at end of file
diff --git a/rpgsaga/saga/src/index.ts b/rpgsaga/saga/src/index.ts
index 7bc4a71de..2fcf9bea3 100644
--- a/rpgsaga/saga/src/index.ts
+++ b/rpgsaga/saga/src/index.ts
@@ -1 +1,37 @@
-console.log('Hello world');
+import {task19A, task19B} from './math';
+import { Mouse } from './src/labclass2';
+
+
+const a = 2.0;
+const x1 = 1.16;
+const x2 = 1.32;
+const x3 = 1.47;
+const x4 = 1.65;
+const x5 = 1.93;
+let xn = 1.2;
+let xk = 4.2;
+let dx = 0.6;
+const xs: number[] = [x1, x2, x3, x4, x5];
+
+const cat1 = new Mouse('Roly', 5, 'Satin mice','Grey');
+console.log(cat1.getInfo);
+const cat2 = new Kitten('Mickey', 2, 'Yellow-throated mice','Yellow');
+console.log(Cat's name: ${cat3.name});
+console.log(cat3.changeCatName('Tyutya'));
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/rpgsaga/saga/src/labclass2.ts b/rpgsaga/saga/src/labclass2.ts
new file mode 100644
index 000000000..9a3742de2
--- /dev/null
+++ b/rpgsaga/saga/src/labclass2.ts
@@ -0,0 +1,68 @@
+export class Mouse {
+    name: string;
+    age: number;
+    breed: string;
+    color: string;
+
+    constructor(mousename: string, mouseage: number, mousebreed: string, mousecolor: string) {
+        this.name = mousename;
+        this.age = mouseage;
+        this.breed = mousebreed;
+        this.color = mousecolor;
+    }
+
+    get getName(): string {
+        return this.name;
+    }
+
+    set setName(valuename: string) {
+        this.name = valuename;
+    }
+
+    get getAge(): number {
+        return this.age;
+    }
+
+    set setAge(valueage: number) {
+        if (valueage < 0 || valueage > 3) {
+            console.error("Mice can't live that long");
+        } else {
+            this.age = valueage;
+        }
+    }
+
+    get getBreed(): string {
+        return this.breed;
+    }
+
+    set setBreed(valuebreed: string) {
+        this.breed = valuebreed;
+    }
+
+    get getColor(): string {
+        return this.color;
+    }
+
+    set setColor(valuecolor: string) {
+        this.color = valuecolor;
+    }
+
+
+    get getInfo(): string {
+        return `Mouse's name: ${this.name}, mouse's age: ${this.age}, mouse's breed: ${this.breed}, mouse's color: ${this.color}`;
+    }
+
+    changeMouseName(newname: string): void {
+        this.name = newname;
+    }
+
+    whereFrom(): string {
+        if (this.name === 'Mickey') {
+            return "Disneyland";
+        } else if (this.name === "Jerry") {
+            return "Cartoon";
+        } else {
+            return "sorryyy(";
+        }
+    }
+}
diff --git a/rpgsaga/saga/src/math.ts b/rpgsaga/saga/src/math.ts
new file mode 100644
index 000000000..9c589dae8
--- /dev/null
+++ b/rpgsaga/saga/src/math.ts
@@ -0,0 +1,19 @@
+declare interface Math {
+  log10(x: number): number;
+}
+
+function calculate19(a: number, x: number): number {
+return Math.pow(Math.log10(a + x), 2) / Math.pow(a + x, 2);
+}
+
+function task15A(a: number, xn: number, xk: number, dx: number): number[] {
+const results: number[] = [];
+for (let x = xn; x <= xk; x += dx) {
+  results.push(calculate19(a, x));
+}
+return results;
+}
+
+function task15B(a: number, xs: number[]): number[] {
+return xs.map(x => calculate19(a, x));
+}
diff --git a/rpgsaga/saga/src/tests.ts b/rpgsaga/saga/src/tests.ts
new file mode 100644
index 000000000..8f5a6e0bd
--- /dev/null
+++ b/rpgsaga/saga/src/tests.ts
@@ -0,0 +1,36 @@
+import {task19A, task19B} from '../src/math';
+
+
+describe('calculate19', () => {
+    it('...', () => {
+      expect(calculate19(2, 1)).toBeCloseTo(0.0144, 4); 
+    });
+  });
+  
+  describe('task19A', () => {
+    it('...', () => {
+      const a = 2.0;
+      const xn = 1.2;
+      const xk = 4.2;
+      const dx = 0.6;
+      const expectedResults = [0.0249, 0.0233, 0.0214, 0.0195, 0.0179, 0.0163]; 
+      const results = task19A(a, xn, xk, dx);
+      expect(results).toEqual(expectedResults);
+    });
+  });
+  
+  describe('task19B', () => {
+    it('...', () => {
+      const a = 2.0;
+      const x1 = 1.16;
+      const x2 = 1.32;
+      const x3 = 1.47;
+      const x4 = 1.65;
+      const x5 = 1.93;
+      const xs = [x1, x2, x3, x4, x5];
+      const expectedResults = [0.0250, 0.0246, 0.0242, 0.0237, 0.0229];
+      const results = task19B(a, xs);
+      expect(results).toEqual(expectedResults);
+    });
+  });
+  
diff --git a/rpgsaga/saga/tests/lab2tests.ts b/rpgsaga/saga/tests/lab2tests.ts
new file mode 100644
index 000000000..6c604ed1c
--- /dev/null
+++ b/rpgsaga/saga/tests/lab2tests.ts
@@ -0,0 +1,69 @@
+import { Mouse } from '../src';
+
+describe('Mouse', () => {
+  it('should correctly initialize properties in the constructor', () => {
+    const Mouse = new Mouse('Jerry', 1, 'White Mouse', 'White');
+    expect(mouse.getName).toBe('Jerry');
+    expect(mouse.getAge).toBe(1);
+    expect(mouse.getBreed).toBe('White Mouse');
+    expect(mouse.getColor).toBe('White');
+  });
+
+  it('Должен корректно устанавливать и получать имя мыши', () => {
+    const mouse = new Mouse('Jerry', 1, 'White Mouse', 'White');
+    mouse.setName = 'Tom';
+    expect(mouse.getName).toBe('Tom');
+  });
+
+  it('Должен вывести ошибку, если указан неверный возраст', () => {
+    const mouse = new Mouse('Jerry', 1, 'White Mouse', 'White');
+    console.error = jest.fn();
+    mouse.setAge = 10;
+    expect(console.error).toHaveBeenCalledWith("Mice can't live that long");
+    expect(mouse.getAge).toBe(1);
+
+    mouse.setAge = -1;
+    expect(console.error).toHaveBeenCalledWith("Mice can't live that long");
+    expect(mouse.getAge).toBe(1);
+  });
+
+  it('Должен корректно устанавливать и получать возраст мыши', () => {
+    const mouse = new Mouse('Jerry', 1, 'White Mouse', 'White');
+    mouse.setAge = 2;
+    expect(mouse.getAge).toBe(2);
+  });
+
+
+  it('Должен корректно устанавливать и получать породу мыши', () => {
+    const mouse = new Mouse('Jerry', 1, 'White Mouse', 'White');
+    mouse.setBreed = 'Black Mouse';
+    expect(mouse.getBreed).toBe('Black Mouse');
+  });
+
+  it('Должен корректно устанавливать и получать цвет мыши', () => {
+    const mouse = new Mouse('Jerry', 1, 'White Mouse', 'White');
+    mouse.setColor = 'Gray';
+    expect(mouse.getColor).toBe('Gray');
+  });
+
+  it('Должен получать полную информацию о мыши', () => {
+    const mouse = new Mouse('Jerry', 1, 'White Mouse', 'White');
+    expect(mouse.getInfo).toBe("Мышонка зовут Джерри, возраст мышонка: 1 год, порода мышонка: Белый мышонок, окрас мышонка: Белый");
+  });
+
+  it('Должен корректно изменять имя мыши', () => {
+    const mouse = new Mouse('Jerry', 1, 'White Mouse', 'White');
+    mouse.changeMouseName('Tom');
+    expect(mouse.getName).toBe('Tom');
+  });
+
+  it('Должен корректно определять происхождение мыши', () => {
+    const mouse1 = new Mouse('Mickey', 2, 'White Mouse', 'White');
+    const mouse2 = new Mouse('Jerry', 1, 'White Mouse', 'White');
+    const mouse3 = new Mouse('Minnie', 6, 'White Mouse', 'White');
+
+    expect(mouse1.whereFrom()).toBe("Disneyland");
+    expect(mouse2.whereFrom()).toBe("Cartoon");
+    expect(mouse3.whereFrom()).toBe("sorryyy(");
+  });
+});
diff --git a/rpgsaga/saga/tests/testslab1.ts b/rpgsaga/saga/tests/testslab1.ts
new file mode 100644
index 000000000..8f5a6e0bd
--- /dev/null
+++ b/rpgsaga/saga/tests/testslab1.ts
@@ -0,0 +1,36 @@
+import {task19A, task19B} from '../src/math';
+
+
+describe('calculate19', () => {
+    it('...', () => {
+      expect(calculate19(2, 1)).toBeCloseTo(0.0144, 4); 
+    });
+  });
+  
+  describe('task19A', () => {
+    it('...', () => {
+      const a = 2.0;
+      const xn = 1.2;
+      const xk = 4.2;
+      const dx = 0.6;
+      const expectedResults = [0.0249, 0.0233, 0.0214, 0.0195, 0.0179, 0.0163]; 
+      const results = task19A(a, xn, xk, dx);
+      expect(results).toEqual(expectedResults);
+    });
+  });
+  
+  describe('task19B', () => {
+    it('...', () => {
+      const a = 2.0;
+      const x1 = 1.16;
+      const x2 = 1.32;
+      const x3 = 1.47;
+      const x4 = 1.65;
+      const x5 = 1.93;
+      const xs = [x1, x2, x3, x4, x5];
+      const expectedResults = [0.0250, 0.0246, 0.0242, 0.0237, 0.0229];
+      const results = task19B(a, xs);
+      expect(results).toEqual(expectedResults);
+    });
+  });
+