diff --git a/01/app.js b/01/app.js
index e69de29..73bb077 100644
--- a/01/app.js
+++ b/01/app.js
@@ -0,0 +1,6 @@
+function showTime() {
+    const time = (new Date()).toLocaleTimeString();
+    console.log(time);
+}
+
+showTime();
diff --git a/02/app.js b/02/app.js
index e69de29..b86ef8c 100644
--- a/02/app.js
+++ b/02/app.js
@@ -0,0 +1,4 @@
+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..863dadf 100644
--- a/03/app.js
+++ b/03/app.js
@@ -0,0 +1,10 @@
+const sumNumbersUpTo = function(n) {
+    let sum = 0;
+    for (let i = 1; i <= n; i++) {
+        sum += i;
+    }
+    return sum;
+};
+
+const result = sumNumbersUpTo(4);
+console.log(result); 
\ No newline at end of file
diff --git a/04/app.js b/04/app.js
index e69de29..7128467 100644
--- a/04/app.js
+++ b/04/app.js
@@ -0,0 +1,16 @@
+function runTimer() {
+  let counter = 0;
+
+  const intervalId = setInterval(function () {
+    const time = new Date().toLocaleTimeString();
+    console.log(time);
+
+    counter++;
+
+    if (counter === 5) {
+      clearInterval(intervalId);
+    }
+  }, 5000);
+}
+
+runTimer();