diff --git a/10_fibonacci/fibonacci.js b/10_fibonacci/fibonacci.js
index bb2c8cc..fb278ac 100644
--- a/10_fibonacci/fibonacci.js
+++ b/10_fibonacci/fibonacci.js
@@ -1,5 +1,11 @@
-const fibonacci = function() {
-
+const fibonacci = function(number, b) {
+    let sum;
+    for (let i = 0, a = 1, b = 1;
+         i < number - 2;
+         i++, (i % 2 == 0) ? a = sum : b = sum) {
+        sum = a + b;
+    }
+    return sum;
 };
 
 // Do not edit below this line
diff --git a/10_fibonacci/fibonacci.spec.js b/10_fibonacci/fibonacci.spec.js
index de632d8..caedfdf 100644
--- a/10_fibonacci/fibonacci.spec.js
+++ b/10_fibonacci/fibonacci.spec.js
@@ -4,16 +4,16 @@ describe('fibonacci', () => {
   test('4th fibonacci number is 3', () => {
     expect(fibonacci(4)).toBe(3);
   });
-  test.skip('6th fibonacci number is 8', () => {
+  test('6th fibonacci number is 8', () => {
     expect(fibonacci(6)).toBe(8);
   });
-  test.skip('10th fibonacci number is 55', () => {
+  test('10th fibonacci number is 55', () => {
     expect(fibonacci(10)).toBe(55);
   });
-  test.skip('15th fibonacci number is 610', () => {
+  test('15th fibonacci number is 610', () => {
     expect(fibonacci(15)).toBe(610);
   });
-  test.skip('25th fibonacci number is 75025', () => {
+  test('25th fibonacci number is 75025', () => {
     expect(fibonacci(25)).toBe(75025);
   });
   test.skip('0th fibonacci number is 0', () => {