diff --git a/01/app.js b/01/app.js
index e69de29..710f0f4 100644
--- a/01/app.js
+++ b/01/app.js
@@ -0,0 +1,6 @@
+function showTime() {
+  const time = new Date().toLocaleDateString();
+  console.log(time);
+}
+
+showTime();
diff --git a/02/app.js b/02/app.js
index e69de29..c810c4d 100644
--- a/02/app.js
+++ b/02/app.js
@@ -0,0 +1,5 @@
+function sayHello(name) {
+  console.log(`Cześć ${name}!`);
+}
+
+sayHello("devmentor.pl");
diff --git a/03/app.js b/03/app.js
index e69de29..97e79c2 100644
--- a/03/app.js
+++ b/03/app.js
@@ -0,0 +1,16 @@
+const sumNum = function (num) {
+  let resultStr = "";
+  let sum = 0;
+  for (let i = 1; i <= num; i++) {
+    sum += i;
+    resultStr += i;
+    if (i == num) {
+      break;
+    }
+    resultStr += "+";
+  }
+  resultStr += "=" + sum;
+  return resultStr;
+};
+
+console.log(sumNum(4));
diff --git a/04/app.js b/04/app.js
index e69de29..89b1e70 100644
--- a/04/app.js
+++ b/04/app.js
@@ -0,0 +1,14 @@
+let idInterval;
+let counter = 0;
+
+runTimer = function () {
+  counter++;
+  if (counter > 5) {
+    clearInterval(idInterval);
+    console.log("Timer has been ended.");
+    return;
+  }
+  console.log(`${counter}: ${Date()}`);
+};
+
+idInterval = setInterval(runTimer, 5000);