diff --git a/module-1/classification.js b/module-1/classification.js
index 9f85b22..0a78d9d 100644
--- a/module-1/classification.js
+++ b/module-1/classification.js
@@ -22,7 +22,23 @@ function grade(score) {
      */
     // PLACE YOUR CODE BETWEEN THIS...
 
-    // ...AND THIS COMMENT LINE!
+    if (score < 0 || score > 100) {
+        gradeOfStudent = 0;
+    }
+    else {
+        gradeOfStudent = Math.ceil(Math.max(((score - 59) / 41) * 4, 0)) + 1;
+    }
+   
+ // ...AND THIS COMMENT LINE!
+ 
     return gradeOfStudent;
 }
-module.exports = grade;
\ No newline at end of file
+
+
+
+
+
+
+
+
+module.exports = grade;
diff --git a/module-1/euclidean.js b/module-1/euclidean.js
index 3d33d00..25b782a 100644
--- a/module-1/euclidean.js
+++ b/module-1/euclidean.js
@@ -16,9 +16,21 @@ function euclidean(a, b) {
      * Also take into consideration the documentation of the function!
      */
     // PLACE YOUR CODE BETWEEN THIS...
-
+    if (a > 0 && b > 0) {
+        while (a !== b) {
+            if (a > b) {
+                a = a - b;
+            } else {
+                b = b - a;
+            }
+        }
+        gcd = a;
+    } else {
+        gcd = 0;
+    }
 
     // ...AND THIS COMMENT LINE!
     return gcd;
 }
-module.exports = euclidean;
\ No newline at end of file
+module.exports = euclidean;
+
diff --git a/module-1/fibonacci.js b/module-1/fibonacci.js
index 14ec907..0aa904f 100644
--- a/module-1/fibonacci.js
+++ b/module-1/fibonacci.js
@@ -15,8 +15,25 @@ function fibonacci(n) {
      * Also take into consideration the documentation of the function!
      */
     // PLACE YOUR CODE BETWEEN THIS...
-
+    if (n >= 0) {
+        if (n < 2) {
+            nThFibonacci = n;
+        } else {
+            let f0 = 0;
+            let f1 = 1;
+            for (let i = 2; i <= n; ++i) {
+                const sum = f0 + f1;
+                f0 = f1;
+                f1 = sum;
+            }
+            nThFibonacci = f1;
+        }
+    } else {
+        nThFibonacci = 0;
+    }
     // ...AND THIS COMMENT LINE!
     return nThFibonacci;
 }
-module.exports = fibonacci;
\ No newline at end of file
+
+module.exports = fibonacci;
+
diff --git a/module-2/test/calc.spec.js b/module-2/test/calc.spec.js
index c6fc7c7..6907f6f 100644
--- a/module-2/test/calc.spec.js
+++ b/module-2/test/calc.spec.js
@@ -1,3 +1,4 @@
+const { Then } = require('cucumber');
 const calc = require('../calc');
 const expect = require('chai').expect;
 
@@ -17,5 +18,144 @@ describe.only('calc', () => {
      *     .times(6).v // 24
      */
     // TODO: write test cases to test calculator
+    it("should have proper value", () => {
+        //Given
+        const c = calc(3);
+        //When
+        //Then
+        expect(c.v).to.equal(3);
+    });
 
-});
\ No newline at end of file
+    describe("add", () => {
+        it("should exist", () => {
+             //Given
+             const c = calc(3);
+             //When
+             //Then
+             expect(c.add).not.to.undefined;
+        });
+        it("should be able to add a number to the current value", () => {
+            //Given
+            const c = calc(3);
+            //When
+            const result = calc(3).add(5);
+            //Then
+            expect(result.v).to.equal(8);
+        });
+    });
+
+    describe("minus", () => {
+        it("should exist", () => {
+            //Given
+            const c = calc(3);
+            //When
+            //Then
+            expect(c.minus).not.to.undefined;
+        });
+        it("should be able to subtract a number from the current value", () => {
+            //Given
+            const c = calc(3);
+            //When
+            const result = calc(3).minus(2);
+            //Then
+            expect(result.v).to.equal(1);
+        });
+    });
+   
+    describe("divide", () => {
+        it("should exist", () => {
+            //Given
+            const c = calc(42);
+            //When
+            //THen
+            expect(c.divide).not.to.undefined;
+        });
+        it("should be able to perform a valid division", () => {
+            //Given
+            const c = calc(10);
+            //When
+            const result = c.divide(2).v;
+            //Then
+            expect(result).to.be.equal(5);
+        });
+        it("should handle division by 0", () => {
+            //Given
+            const c = calc(5);
+            //When
+            //Then
+            expect(() => c.divide(0)).to.throw("Division by 0 is not possible!");
+        });
+    });
+
+    describe("sqrt", () => {
+        it("should exist", () => {
+            //Given
+            const c = calc(4);
+            //When
+            //THen
+            expect(c.sqrt).not.to.undefined;
+        });
+        it("should be able to square a number", () => {
+            //Given
+            const c = calc(4);
+            //When
+            const result = calc(4).sqrt().v;
+            //Then
+            expect(result).to.equal(2);
+        });
+        it ("should handle negative numbers", () => {
+            //Given
+            const c = calc(-3);
+            //When
+            //Then
+            expect(() => c.sqrt()).to.throw("Square root of negative value cannot be determined!");
+        });
+    });
+
+    describe("times", () => {
+        it("should exist", () => {
+            //Given
+            const c = calc(4);
+            //When
+            //THen
+            expect(c.times).not.to.undefined;
+        });
+        it("should be able to multiply numbers", () => {
+            //Given
+            const c = calc(3);
+            //When
+            const result = calc(3).times(10).v;
+            //Then
+            expect(result).to.equal(30);
+        });
+    });
+
+    describe("modulo", () => {
+        it("should exist", () => {
+            //Given
+            const c = calc(10);
+            //When
+            //THen
+            expect(c.modulo).not.to.undefined;
+        });
+        it("should be able to perform modulo operation", () => {
+            //Given
+            const c = calc(10);
+            //When
+            const result = c.modulo(5).v;
+            //Then
+            expect(result).to.equal(0);
+        });
+    });
+
+    describe("multiply operations", () => {
+        it("should be able to perform multiply operations", () => {
+            //Given
+            const c = calc(3);
+            //When
+            const result = c.add(4).minus(3).times(6).v;
+            //THen
+            expect(result).to.equal(24);
+        });
+    });
+});