diff --git a/01/app.js b/01/app.js
index e69de29..9b23dd8 100644
--- a/01/app.js
+++ b/01/app.js
@@ -0,0 +1,10 @@
+const users = new Array("John Doe", "John Smith", "Joe Bonamassa", "Mia Davis", "Ava Miller");
+
+
+console.log(`Pierwsza pozycja w zmiennej 'users' to: ${users[0]}`);
+console.log(`Trzecia pozycja w zmiennej 'users' to: ${users[2]}`);
+console.log(`Piąta pozycja w zmiennej 'users' to: ${users[4]}`);
+
+
+console.log(`Zmienna 'users' zawiera: ${users.length} pozycji`);
+
diff --git a/02/app.js b/02/app.js
index 9ad302b..1e9f99f 100644
--- a/02/app.js
+++ b/02/app.js
@@ -2,6 +2,15 @@ const randomArray = createRandomArray();
 console.log(randomArray);
 
 
+for (let j = 0; j < randomArray.length; j++) {
+    console.log(`Pozycja nr ${j + 1}: ${randomArray[j]} === for(){} ===`);
+};
+
+randomArray.forEach((e, i) => {
+    console.log(`Pozycja nr ${i + 1}: ${e} === forEach() ===`);
+});
+
+console.log(`Ostatnia pozycja w 'randomArray to: '${randomArray[randomArray.length - 1]}`);
 
 // nie modyfikuj kodu poniżej!
 
@@ -11,13 +20,13 @@ console.log(randomArray);
 function createRandomArray() {
     const arr = [];
     const len = getRandomInteger(1, 10)
-    for(let i=0; i<len; i++) {
-        arr.push( getRandomInteger(1, 100) );
+    for (let i = 0; i < len; i++) {
+        arr.push(getRandomInteger(1, 100));
     }
 
     return arr;
 }
 
 function getRandomInteger(min, max) {
-    return Math.round(Math.random() * (max-min) + min);
+    return Math.round(Math.random() * (max - min) + min);
 }
\ No newline at end of file
diff --git a/03/app.js b/03/app.js
index cebcbc2..c236eff 100644
--- a/03/app.js
+++ b/03/app.js
@@ -1,2 +1,16 @@
 const n = 24;
-const oddNumbers = [];
\ No newline at end of file
+const oddNumbers = [];
+
+if (n <= 0) {
+  console.log('Zmienna "n" jest mniejsza lub równa zeru!');
+} else {
+  for (let i = 0; i <= n; i++) {
+    if (i % 2 !== 0) {
+      oddNumbers.push(i);
+    }
+  }
+};
+
+oddNumbers.forEach((e, i) => {
+  console.log(`Index: ${i}; Wartość: ${e}`);
+});
\ No newline at end of file
diff --git a/04/app.js b/04/app.js
index 8285afd..b142933 100644
--- a/04/app.js
+++ b/04/app.js
@@ -1 +1,12 @@
-const years = [1980, 1934, 2002, 2019];
\ No newline at end of file
+const years = [1980, 1934, 2002, 2019];
+
+const yearPoint = parseInt(prompt('Podaj rok, który będzie punktem odniesienia'));
+
+if (!yearPoint | yearPoint < 0) {
+  alert('Wprowadzono niepoprawny format danych odśwież stronę i spróbuj jeszcze raz!');
+} else {
+  const newYears = years.map((e) => e - yearPoint);
+  newYears.forEach((e, i) => {
+    console.log(`Między datą nr. ${i + 1} a punktem odniesienia jest ${e} lat różnicy`)
+  });
+}
\ No newline at end of file
diff --git a/05/app.js b/05/app.js
index 1c6bb90..394c321 100644
--- a/05/app.js
+++ b/05/app.js
@@ -1 +1,9 @@
-const numbers = [1, 2, 3, 4, 5, 6, 7];
\ No newline at end of file
+const numbers = [1, 2, 3, 4, 5, 6, 7];
+
+const evenNumbers = numbers.filter(e => e % 2 === 0);
+
+const sum = evenNumbers.reduce((total, currentValue) => {
+  return total += currentValue
+});
+
+console.log(`The sum of the even numbers inside "numbers" array is: ${sum}`);
\ No newline at end of file