diff --git a/01/app.js b/01/app.js
index e69de29..4724aec 100644
--- a/01/app.js
+++ b/01/app.js
@@ -0,0 +1,5 @@
+function showTime() {
+  const time = new Date().toLocaleTimeString();
+  console.log(time);
+}
+showTime();
diff --git a/02/app.js b/02/app.js
index e69de29..5e02a51 100644
--- a/02/app.js
+++ b/02/app.js
@@ -0,0 +1,4 @@
+function sayHello(name) {
+  console.log('Cześć ' + name + '!');
+}
+sayHello('devmentor.pl');
diff --git a/03/app.js b/03/app.js
index e69de29..7f2eeb6 100644
--- a/03/app.js
+++ b/03/app.js
@@ -0,0 +1,9 @@
+const fn = function (a) {
+  let sum = 0;
+  for (let i = 1; i <= a; i++) {
+    sum += i;
+  }
+  return sum;
+};
+
+console.log(fn(4));
diff --git a/04/app.js b/04/app.js
index e69de29..a559e4b 100644
--- a/04/app.js
+++ b/04/app.js
@@ -0,0 +1,14 @@
+let idInterval;
+let counter = 0;
+
+function runTimer() {
+  const time = new Date().toLocaleTimeString();
+  console.log(time);
+
+  counter++;
+
+  if (counter >= 5) {
+    clearInterval(idInterval);
+  }
+}
+idInterval = setInterval(runTimer, 5000);