diff --git a/src/factorial.js b/src/factorial.js
index 4f3ae70..bb9f2bb 100644
--- a/src/factorial.js
+++ b/src/factorial.js
@@ -1,5 +1,6 @@
-const factorial = (number) => {
-  // your code here
-}
+const factorial = number => {
+  if (number < 1) return 1;
+  return factorial(number - 1) * number;
+};
 
-module.exports = factorial;
\ No newline at end of file
+module.exports = factorial;
diff --git a/src/fibonacci.js b/src/fibonacci.js
index ea3270f..f21f6d5 100644
--- a/src/fibonacci.js
+++ b/src/fibonacci.js
@@ -1,5 +1,18 @@
-const fibonacci = (n) => {
-  // your code here
-}
+const fibonacci = n => {
+  if (n < 1) return [0];
 
-module.exports = fibonacci;
\ No newline at end of file
+  const resultsArr = [0, 1];
+  let prev = 0;
+  let current = 1;
+
+  while (current !== n) {
+    current = prev + current;
+    if (current > n) return resultsArr;
+    resultsArr.push(current);
+    prev = current - prev;
+  }
+
+  return resultsArr;
+};
+
+module.exports = fibonacci;
diff --git a/src/primalidad.js b/src/primalidad.js
index 8bdb849..afaca28 100644
--- a/src/primalidad.js
+++ b/src/primalidad.js
@@ -1,5 +1,14 @@
-const trialDivision = (number) => {
-  // your code here
-}
+const trialDivision = number => {
+  const factorsArr = [];
+  let factor = 2;
 
-module.exports = trialDivision;
\ No newline at end of file
+  while (number > 1) {
+    if (number % factor === 0) {
+      factorsArr.push(factor);
+      number /= factor;
+    } else factor += 1;
+  }
+  return factorsArr.length === 1;
+};
+
+module.exports = trialDivision;