diff --git a/modules/2_functions/index.js b/modules/2_functions/index.js
index 5f4ac95..9e22dd8 100644
--- a/modules/2_functions/index.js
+++ b/modules/2_functions/index.js
@@ -6,22 +6,55 @@ export const mergeWords = () => {};
 /**
  * Every/Some
  */
-export const checkUsersValid = () => {};
+export const checkUsersValid = (originUsers) => {
+    function checkUsers(users){
+        let originIds = originUsers.map((user) => user.id);
+          
+        for(const user of users) {
+            if(!originIds.includes(user.id)) return false;
+        }
+        return true;
+    }
+    return checkUsers;
+};
 
 /**
  * Reduce 
  */
-export const countWords = () => {};
+export const countWords = (words) => {
+    function updateObjectProperty(obj, word){
+        obj[word] = (obj[word] || 0) + 1;
+        return obj;
+    }
+    return words.reduce((obj, word) => updateObjectProperty(obj, word), new Object());
+};
 
 /**
  * Palindrome 
  */
-export const isPalindrome = () => {};
+export const isPalindrome = (str) => {
+    let reverseStr = str.toLowerCase().split('').reverse().join('');
+    return str.toLowerCase() === reverseStr ? "The entry is a palindrom":"Entry is not a palindrome";
+};
 
 /**
  * Recursion 
  */
-export const factorial = () => {};
+export const factorial = (num) => {
+    if (num === 0) {
+        return 1;
+    }
+    else { 
+        return num * factorial( num - 1 ); 
+    }
+};
 export const amountToCoins = () => {};
-export const repeat = () => {};
+export const repeat = (fn, times) => {
+    if(times <= 0){
+        return;
+    }
+
+    fn.call();
+    repeat(fn, --times);
+};
 export const reduce = () => {};