diff --git a/Exercises/1-let.js b/Exercises/1-let.js
index d705443..dee9f11 100644
--- a/Exercises/1-let.js
+++ b/Exercises/1-let.js
@@ -1,5 +1,5 @@
 'use strict';
 
-let name = undefined;
+let name = 'Vitaliy Korolyk';
 
 module.exports = { name };
diff --git a/Exercises/2-const.js b/Exercises/2-const.js
index 5512738..c647183 100644
--- a/Exercises/2-const.js
+++ b/Exercises/2-const.js
@@ -1,5 +1,5 @@
 'use strict';
 
-const year = undefined;
+const year = 1995;
 
 module.exports = { year };
diff --git a/Exercises/3-hello.js b/Exercises/3-hello.js
index a597391..5432eef 100644
--- a/Exercises/3-hello.js
+++ b/Exercises/3-hello.js
@@ -1,5 +1,4 @@
 'use strict';
 
-const hello = null;
-
+const hello = name =>  console.log(`Hello ${name}`);
 module.exports = { hello };
diff --git a/Exercises/4-range copy.js b/Exercises/4-range copy.js
new file mode 100644
index 0000000..5d3a6b8
--- /dev/null
+++ b/Exercises/4-range copy.js	
@@ -0,0 +1,11 @@
+'use strict';
+
+const range = (start, end) => {
+  const arr = [];
+  for (let i = 0; i <= end - start; i++) {
+    arr[i] = start + i;
+  }
+  return arr;
+};
+range(15, 30);
+module.exports = { range };
diff --git a/Exercises/4-range.js b/Exercises/4-range.js
index 31bd852..5d3a6b8 100644
--- a/Exercises/4-range.js
+++ b/Exercises/4-range.js
@@ -1,5 +1,11 @@
 'use strict';
 
-const range = null;
-
+const range = (start, end) => {
+  const arr = [];
+  for (let i = 0; i <= end - start; i++) {
+    arr[i] = start + i;
+  }
+  return arr;
+};
+range(15, 30);
 module.exports = { range };
diff --git a/Exercises/5-range-odd.js b/Exercises/5-range-odd.js
index 54bb5b4..f0712c7 100644
--- a/Exercises/5-range-odd.js
+++ b/Exercises/5-range-odd.js
@@ -1,5 +1,14 @@
 'use strict';
 
-const rangeOdd = null;
+const rangeOdd = (start, end) => {
+  const arr = [];
+  for (let i = start; i <= end; i++) {
+    if (i % 2 !== 0) {
+      arr.push(i);
+    }
+  }
+  return arr;
+};
 
 module.exports = { rangeOdd };
+
diff --git a/Exercises/6-calculate.js b/Exercises/6-calculate.js
index dfecf6b..fd4a5a8 100644
--- a/Exercises/6-calculate.js
+++ b/Exercises/6-calculate.js
@@ -1,11 +1,22 @@
 'use strict';
 
-const square = null;
+const square = x => x * x;
 
-const cube = null;
+const cube = x => x ** 3;
 
-const average = null;
+const average = (a, b) => (a + b) / 2;
 
-const calculate = null;
+const arr = [];
+
+const calculate = () => {
+  for (let i = 0; i <= 9; i++) {
+    const s = square(i);
+    const c = cube(i);
+    arr[i] = average(s, c);
+  }
+  return arr;
+};
+
+calculate(3);
 
 module.exports = { square, cube, average, calculate };
diff --git a/Exercises/7-objects.js b/Exercises/7-objects.js
index 0920026..33f0a1c 100644
--- a/Exercises/7-objects.js
+++ b/Exercises/7-objects.js
@@ -1,5 +1,10 @@
 'use strict';
 
-const fn = null;
-
+const fn = () => {
+  const obj1 = { name: 'Vitalik' };
+  let obj2 = { name: 'Oleg' };
+  obj1.name = 'Oleg';
+  obj2.name = 'Vitalik';
+  obj2 = { name: 'Serge' };
+};
 module.exports = { fn };
diff --git a/Exercises/8-create.js b/Exercises/8-create.js
index ac27ddd..9e8fcd0 100644
--- a/Exercises/8-create.js
+++ b/Exercises/8-create.js
@@ -1,5 +1,11 @@
 'use strict';
 
-const createUser = null;
-
+const createUser = (name, city) => {
+  const obj = {
+    name,
+    city,
+  };
+  return obj;
+};
+createUser('Mark', 'Brody');
 module.exports = { createUser };
diff --git a/Exercises/9-array.js b/Exercises/9-array.js
index 466c69a..185916b 100644
--- a/Exercises/9-array.js
+++ b/Exercises/9-array.js
@@ -1,7 +1,13 @@
 'use strict';
 
-const phonebook = null;
-
-const findPhoneByName = null;
+const phonebook = [
+  { name: 'Vitalik', phone: '1234' },
+  { name: 'Oleg', phone: '4321' },
+];
 
+const findPhoneByName = name => {
+  for (const x of phonebook) {
+    if (x.name === name)  return x.phone;
+  }
+};
 module.exports = { phonebook, findPhoneByName };
diff --git a/Exercises/a-hash.js b/Exercises/a-hash.js
index 466c69a..e657a9f 100644
--- a/Exercises/a-hash.js
+++ b/Exercises/a-hash.js
@@ -1,7 +1,11 @@
 'use strict';
 
-const phonebook = null;
+const phonebook = {
+  Vitalik: 1234,
+  Oleg: 4321,
+};
 
-const findPhoneByName = null;
+const findPhoneByName = name =>  phonebook[name];
+findPhoneByName('Oleg');
 
 module.exports = { phonebook, findPhoneByName };