diff --git a/lesson_06/README.md b/lesson_06/README.md
index 2dd23c143..f696f7e5e 100644
--- a/lesson_06/README.md
+++ b/lesson_06/README.md
@@ -58,7 +58,7 @@ function isValidAlphaAbbreviation(word: string, abbr: string): boolean
 
 Example 1:
 ```
-Input: word = "internationalization", abbr = "irzdn"
+Input: word = "internationalization", abbr = "imzdn"
 Output: true
 Explanation: 
 - "internationalization" can be abbreviated as "i m z d n"
diff --git a/lesson_06/expression/.env.test b/lesson_06/expression/.env.test
index 56cf4a06f..9fd9f468b 100644
--- a/lesson_06/expression/.env.test
+++ b/lesson_06/expression/.env.test
@@ -1 +1 @@
-HW_VERSION=your assigned version here
\ No newline at end of file
+HW_VERSION=E
\ No newline at end of file
diff --git a/lesson_06/expression/src/abbreviation.ts b/lesson_06/expression/src/abbreviation.ts
new file mode 100644
index 000000000..d8b2d0d18
--- /dev/null
+++ b/lesson_06/expression/src/abbreviation.ts
@@ -0,0 +1,75 @@
+/**
+ * Utility class for checking alphabet-based abbreviations.
+ *
+ * An abbreviation is considered valid if:
+ * - It starts and ends with the same character as the word.
+ * - It correctly skips letters based on alphabetical offsets.
+ */
+export class Abbreviation {
+  /**
+   * Determines whether a given abbreviation is valid for a given word.
+   *
+   * The abbreviation alternates between:
+   * - a "number" step: an abbreviation character represents a skip of positions in the word.
+   * - a "letter" step: the abbreviation character must directly match the word.
+   *
+   * @param {string} word - The full word to validate against.
+   * @param {string} abbr - The abbreviation to check.
+   * @return {boolean} True if the abbreviation is valid for the word, false otherwise.
+   */
+  isValidAlphaAbbreviation(word: string, abbr: string): boolean {
+    if (word.length < abbr.length) {
+      return false;
+    }
+
+    // First and last characters must match.
+    if (
+      word[0] !== abbr[0] ||
+      word[word.length - 1] !== abbr[abbr.length - 1]
+    ) {
+      return false;
+    }
+
+    let num = true;
+    let wordIndex = 1;
+    let abbrIndex = 1;
+
+    while (wordIndex < word.length && abbrIndex < abbr.length) {
+      // If num is true, treat the abbreviation character as a number.
+      // If num is false, treat it as a letter.
+      if (num) {
+        // Interpret abbreviation character as a skip.
+        const skip = abbr[abbrIndex].charCodeAt(0) - "a".charCodeAt(0) + 1;
+        const newWordIndex = wordIndex + skip;
+        // If out of bounds, check if it matches the last character.
+        if (newWordIndex >= word.length) {  
+          if (word[wordIndex] !== abbr[abbrIndex]) {
+            return false;
+          }
+          wordIndex++;
+        } else {
+          wordIndex = newWordIndex;
+          num = false;
+        }
+        abbrIndex++;
+      } else {
+        // Match letters if num isn't true.
+        if (word[wordIndex] !== abbr[abbrIndex]) {
+          return false;
+        }
+        wordIndex++;
+        abbrIndex++;
+        num = true;
+      }
+    }
+
+    return wordIndex === word.length && abbrIndex === abbr.length;
+  }
+}
+
+// Example usage:
+const abbrChecker = new Abbreviation();
+console.log(abbrChecker.isValidAlphaAbbreviation("internationalization", "irn"),); // true
+console.log(abbrChecker.isValidAlphaAbbreviation("internationalization", "imzdn"),); // true
+console.log(abbrChecker.isValidAlphaAbbreviation("apple", "abe")); // false
+console.log(abbrChecker.isValidAlphaAbbreviation("bags", "bas")); // false
diff --git a/lesson_06/expression/src/expression_calculator.ts b/lesson_06/expression/src/expression_calculator.ts
index 76b215c42..1d9cab668 100644
--- a/lesson_06/expression/src/expression_calculator.ts
+++ b/lesson_06/expression/src/expression_calculator.ts
@@ -1,11 +1,25 @@
 export class ExpressionCalculator {
   /** Returns a calculation involving a, b, c, d, and e */
   calculate(a: number, b: number, c: number, d: number, e: number): number {
-    // Implement your code here to return the correct value.
-    return 0;
+    return this.multiply(this.pow(this.divide(this.add(a,b), c), d),e);
   }
 
+  add(a: number, b: number): number {
+    return a + b;
+  }
+  subtract(a: number, b: number): number {
+    return a - b;
+  }
+  multiply(a: number, b: number): number {
+    return a * b;
+  }
+  divide(a: number, b: number): number {
+    if (b === 0) {
+      throw new Error("Division by zero is not allowed.");
+    }
+    return a / b;
+  }
   pow(base: number, exponent: number): number {
     return Math.pow(base, exponent);
   }
-}
+}
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