diff --git a/01/app.js b/01/app.js
index e69de29..2902741 100644
--- a/01/app.js
+++ b/01/app.js
@@ -0,0 +1,6 @@
+const showTime = () => {
+  const time = new Date().toLocaleTimeString();
+  console.log('Twój aktualny czas  to:', time);
+};
+
+showTime();
diff --git a/02/app.js b/02/app.js
index e69de29..822c01a 100644
--- a/02/app.js
+++ b/02/app.js
@@ -0,0 +1,5 @@
+const sayHello = (name) => {
+  console.log(name);
+};
+
+sayHello('Hello, devmentor.pl!');
diff --git a/03/app.js b/03/app.js
index e69de29..663ff96 100644
--- a/03/app.js
+++ b/03/app.js
@@ -0,0 +1,12 @@
+const sum = function (number) {
+  let result = 0;
+
+  for (let i = 1; i <= number; i++) {
+    result = result + i;
+  }
+
+  return result;
+};
+
+const sumNumber = sum(4);
+console.log('Wynik sumy to:', sumNumber);
diff --git a/04/app.js b/04/app.js
index e69de29..df4fd75 100644
--- a/04/app.js
+++ b/04/app.js
@@ -0,0 +1,15 @@
+let idInterval;
+let counter = 0;
+
+const runTimer = function () {
+  let time = new Date().toLocaleTimeString();
+  counter++;
+
+  if (counter <= 5) {
+    console.log(time);
+  } else {
+    clearInterval(idInterval);
+  }
+};
+
+idInterval = setInterval(runTimer, 5000);