diff --git a/01/app.js b/01/app.js
index e69de29..52b8192 100644
--- a/01/app.js
+++ b/01/app.js
@@ -0,0 +1,6 @@
+const showTime = function() {
+    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..e6b18c3 100644
--- a/02/app.js
+++ b/02/app.js
@@ -0,0 +1,6 @@
+const sayHello = function(userName) {
+    console.log("Cześć", userName, "!");
+}
+
+sayHello('devmentor.pl');
+
diff --git a/03/app.js b/03/app.js
index e69de29..7eb4903 100644
--- a/03/app.js
+++ b/03/app.js
@@ -0,0 +1,10 @@
+const sumNumbers = function(x) {
+    let result = 0;
+
+    for(let i = 0; i <= x; i++ ) {
+        result += i;
+    }
+
+    return result;
+}
+console.log(sumNumbers(4));
\ No newline at end of file
diff --git a/04/app.js b/04/app.js
index e69de29..e742b29 100644
--- a/04/app.js
+++ b/04/app.js
@@ -0,0 +1,15 @@
+let counter = 0;
+
+const runTimer = function() {
+    const time = (new Date()).toLocaleTimeString();
+    console.log(time);
+    counter++;
+    console.log(counter);
+
+    if(counter >= 5) {
+    clearInterval(intervalId);
+    console.log("Timer stop!");
+    }
+}
+
+const intervalId = setInterval(runTimer, 5000);
\ No newline at end of file