diff --git a/src/task3 - Largest prime factor.js b/src/task3 - Largest prime factor.js
new file mode 100644
index 0000000..ad8f4ea
--- /dev/null
+++ b/src/task3 - Largest prime factor.js	
@@ -0,0 +1,20 @@
+function primeFactorsOf(n) {
+  let k = 2;
+  let factors = [];
+
+  while (n >= k**2) {
+    if (n % k === 0) {
+      factors.push(k)
+      n = n/k;
+    } else {
+      k++;
+    }
+  }
+  factors.push(n);
+  return factors;
+}
+
+const SPECIAL_NUM = 600851475143;
+const factorsOfSpecialNum = primeFactorsOf(SPECIAL_NUM);
+
+console.log(Math.max.apply(null, factorsOfSpecialNum));
\ No newline at end of file