diff --git a/01/app.js b/01/app.js
index e69de29..6b32184 100644
--- a/01/app.js
+++ b/01/app.js
@@ -0,0 +1,5 @@
+function showTime() {
+    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..0b7fbcd 100644
--- a/02/app.js
+++ b/02/app.js
@@ -0,0 +1,5 @@
+function sayHello(text) {
+    console.log('Cześć ' + text + '!');
+}
+
+sayHello('devmentor.pl')
\ No newline at end of file
diff --git a/03/app.js b/03/app.js
index e69de29..8bd90d1 100644
--- a/03/app.js
+++ b/03/app.js
@@ -0,0 +1,11 @@
+const numberOfCycleCounts = function(numberOfCycles) {
+    let sum = 0;
+
+    for (i = 0; i < numberOfCycles; i++) {
+        sum = sum + (i+1);
+    }
+
+    return sum;
+}
+
+console.log(numberOfCycleCounts(4));
\ No newline at end of file
diff --git a/04/app.js b/04/app.js
index e69de29..934d573 100644
--- a/04/app.js
+++ b/04/app.js
@@ -0,0 +1,18 @@
+function runTimer() {
+
+    let idInterval;
+    let counter = 5;
+
+    const time = function() {
+        if (counter == 0) {
+            clearInterval(idInterval);
+        } else {
+            console.log((new Date()).toLocaleTimeString());
+            counter--;
+        }
+    }
+
+    idInterval = setInterval(time,5000);
+
+}
+runTimer();
\ No newline at end of file