diff --git a/01/app.js b/01/app.js
index e69de29..32ef371 100644
--- a/01/app.js
+++ b/01/app.js
@@ -0,0 +1,7 @@
+function showTime(){
+    
+    const time = (new Date()).toLocaleTimeString();
+    console.log(time);
+}
+
+showTime();
\ No newline at end of file
diff --git a/02/app.js b/02/app.js
index e69de29..37898c8 100644
--- a/02/app.js
+++ b/02/app.js
@@ -0,0 +1,5 @@
+function sayHello(name) {
+    console.log(`Cześć ${name}!`);
+}
+
+sayHello('devmentor.pl');
\ No newline at end of file
diff --git a/03/app.js b/03/app.js
index e69de29..286de92 100644
--- a/03/app.js
+++ b/03/app.js
@@ -0,0 +1,11 @@
+const sumNumbers = function(lastNumberToSum) {
+    let sum = 0;
+
+    for (let i = 1; i <= lastNumberToSum; i++){
+        sum += i;
+    }
+    return sum;
+}
+
+
+console.log(sumNumbers(4));
\ No newline at end of file
diff --git a/04/app.js b/04/app.js
index e69de29..1fb8783 100644
--- a/04/app.js
+++ b/04/app.js
@@ -0,0 +1,18 @@
+function runTimer(){
+
+    let counter = 0;
+
+    const myInterval = setInterval(function(){
+        const time = (new Date()).toLocaleTimeString();
+        console.log(time);
+        counter++;
+
+        if(counter > 4) {
+            clearInterval(myInterval)
+        }
+    },5000)
+}
+
+runTimer();
+
+