diff --git a/Exercises/1-let.js b/Exercises/1-let.js
index d705443..ab3f287 100644
--- a/Exercises/1-let.js
+++ b/Exercises/1-let.js
@@ -1,5 +1,5 @@
 'use strict';
 
-let name = undefined;
+let name = 'Urich';
 
 module.exports = { name };
diff --git a/Exercises/2-const.js b/Exercises/2-const.js
index 5512738..1dedd16 100644
--- a/Exercises/2-const.js
+++ b/Exercises/2-const.js
@@ -1,5 +1,5 @@
 'use strict';
 
-const year = undefined;
+const year = 1984;
 
 module.exports = { year };
diff --git a/Exercises/3-hello.js b/Exercises/3-hello.js
index a597391..ef846d3 100644
--- a/Exercises/3-hello.js
+++ b/Exercises/3-hello.js
@@ -1,5 +1,7 @@
 'use strict';
 
-const hello = null;
+const hello = name => {
+  console.log(`Welcome home, ${name}`);
+};
 
 module.exports = { hello };
diff --git a/Exercises/4-range.js b/Exercises/4-range.js
index 31bd852..8d5d30f 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 array = [];
+  for (let i = start; i <= end; i += 1) {
+    array.push(i);
+  }
+  return array;
+};
 
 module.exports = { range };
diff --git a/Exercises/5-range-odd.js b/Exercises/5-range-odd.js
index 54bb5b4..2b00871 100644
--- a/Exercises/5-range-odd.js
+++ b/Exercises/5-range-odd.js
@@ -1,5 +1,11 @@
 'use strict';
 
-const rangeOdd = null;
+const rangeOdd = (start, end) => {
+  const array = [];
+  for (let i = start; i <= end; i += 1) {
+    if (i % 2 !== 0) array.push(i);
+  }
+  return array;
+};
 
 module.exports = { rangeOdd };
diff --git a/Exercises/6-calculate.js b/Exercises/6-calculate.js
index dfecf6b..9e85651 100644
--- a/Exercises/6-calculate.js
+++ b/Exercises/6-calculate.js
@@ -1,11 +1,17 @@
 '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 calculate = () => {
+  const array = [];
+  for (let i = 0; i < 10; i += 1) {
+    array.push(average(square(i), cube(i)));
+  }
+  return array;
+};
 
 module.exports = { square, cube, average, calculate };
diff --git a/Exercises/7-objects.js b/Exercises/7-objects.js
index 0920026..cd311f9 100644
--- a/Exercises/7-objects.js
+++ b/Exercises/7-objects.js
@@ -1,5 +1,14 @@
 'use strict';
 
-const fn = null;
+const fn = () => {
+  const obj1 = { name: 'Jmih' };
+  let obj2 = { name: 'Urich' };
+  const obj3 = { mask: 'NT-200' };
+
+  obj1.name = 'Shpack';
+  obj2.name = 'Seryoja';
+  //obj1 = obj3; //obj1 assigned as a constant
+  obj2 = obj3;
+};
 
 module.exports = { fn };
diff --git a/Exercises/8-create.js b/Exercises/8-create.js
index ac27ddd..52d3503 100644
--- a/Exercises/8-create.js
+++ b/Exercises/8-create.js
@@ -1,5 +1,8 @@
 'use strict';
 
-const createUser = null;
+const createUser = (name, city) => {
+  const user = { name, city };
+  return user;
+};
 
 module.exports = { createUser };
diff --git a/Exercises/9-array.js b/Exercises/9-array.js
index 466c69a..e0e9bb8 100644
--- a/Exercises/9-array.js
+++ b/Exercises/9-array.js
@@ -1,7 +1,17 @@
 'use strict';
 
-const phonebook = null;
+const phonebook = [
+  { name: 'Marcus', phone: '+380445554433' },
+  { name: 'Valeriy', phone: '+380982285427' },
+  { name: 'Denis', phone: '+380665527456' },
+];
 
-const findPhoneByName = null;
+const findPhoneByName = n => {
+  for (const i of phonebook) {
+    if (i.name === n) {
+      return i.phone;
+    }
+  }
+};
 
 module.exports = { phonebook, findPhoneByName };
diff --git a/Exercises/a-hash.js b/Exercises/a-hash.js
index 466c69a..da39bf6 100644
--- a/Exercises/a-hash.js
+++ b/Exercises/a-hash.js
@@ -1,7 +1,13 @@
 'use strict';
 
-const phonebook = null;
+const phonebook = {
+  Jmih: { phone: '+380982285427' },
+  Urich: { phone: '+380661488228' },
+  Denis: { phone: '+380445422827' },
+  Shpack: { phone: '+380541488273' },
+  Sanya: { phone: '+380965042075' }
+};
 
-const findPhoneByName = null;
+const findPhoneByName = name => phonebook[name].phone;
 
 module.exports = { phonebook, findPhoneByName };