diff --git a/functionalty.js b/functionalty.js
index 1110352..274d404 100644
--- a/functionalty.js
+++ b/functionalty.js
@@ -1,74 +1,150 @@
 // Math
+/**
+ * get average between two numbers
+ * 
+ * @param {number} number1 
+ * @param {number} number2 
+ * @returns {number}
+ */
 function getMid(number1, number2) {
   return Math.floor((number1 + number2) / 2)
 }
 
 // Arrays
+
+/**
+ * Filter an array depending on the given value
+ * 
+ * @param {any[]} array
+ * @param {any} value
+ * @returns 
+ */
 function filterArray(array, value) {
   return array.filter(e => e != value);
 }
 
+/**
+ * Get sum of all numbers in array
+ * 
+ * @param {number[]} array array of numbers
+ * @returns {number} sum of all numbers in array
+ */
 function sumOfArray(array) {
   return array.reduce((a, b) => a + b, 0);
 }
 
+/**
+ * Sort an array of numbers in ascending order
+ * 
+ * @param {number[]} array array of numbers
+ */
 function ascending(array) {
   array.sort(function(a, b) {return a - b;});
 }
 
+/**
+ * Sort an array of numbers in descending order
+ * 
+ * @param {number[]} array array of numbers
+ */
 function descending(array) {
   array.sort(function(a, b) {return a - b;}).reverse();
 }
 
+/**
+ * Get minimum value in array
+ * 
+ * @param {number[]} array - Array of numbers
+ * @returns {number}
+ */
 function minArray(array) {
-  let min = null;
-  for (let i = 0; i < array.length; i++) {
-    min == null ? min = array[i] : "";
-    array[i] < min ? min = array[i] : "";
-  }
-  return min;
+  return Math.min(...array); // using math.min() to get minimum value in array is faster than using a for loop
 }
 
+/**
+ * Get maximum value in array
+ * 
+ * @param {number[]} array 
+ * @returns {number}
+ */
 function maxArray(array) {
-  let max = null;
-  for (let i = 0; i < array.length; i++) {
-    max == null ? max = array[i] : "";
-    array[i] > max ? max = array[i] : "";
-  }
-  return max;
+  return Math.max(...array) // using math.max() to get maximum value in array is faster than using a for loop
 }
 
 // Strings
+
+/**
+ * 
+ * @param {string} word string to be reversed
+ * @returns {string}
+ */
 function reverseString(word) {
-  return word.split("").reverse().join();
+  return word.split("").reverse().join("");
+
 }
 
 // Numbers
+
+/**
+ * reverse a number (e.g. 12345 -> 54321)
+ * 
+ * @param {number} number 
+ * @returns {number}
+ */
 function reverseNum(number) {
-  if (number == 0) {
+  // this code is changed from the original one because it didn't work properly when the number is decimal
+  if (number < 10 && number > -10) {
     return number;
   }
-  return Math.floor(parseInt(number)) > 0 ? parseInt(number.toString().split("").reverse().join("")) : parseInt("-" + number.toString().split("").reverse().join(""));
+  const parsedNumber = +(number > 10 ? number : number * -1).toString().split("").reverse().join("");
+  return number > 10 ? parsedNumber : parsedNumber * -1; // this code more readable than the other one also it works with decimals too
 }
 
 // Valid Checks
+
+/**
+ * check if a number is even
+ * 
+ * @param {number} number 
+ * @returns {boolean}
+ */
 function isEven(number) {
   return number % 2 == 0;
 }
 
+/**
+ * check if a number is odd
+ * 
+ * @param {number} number 
+ * @returns {boolean}
+ */
 function isOdd(number) {
   return number % 2 != 0;
 }
 
+/**
+ * check if a string is a palindrome
+ * 
+ * @param {string} word 
+ * @returns {boolean}
+ */
 function isPalindrome(word) {
   return word.toString() == reverseString(word.toString());
 }
 
+/**
+ * check if a number is prime
+ * 
+ * @param {number} number 
+ * @returns {number | boolean}
+ */
 function isPrime(number) {
-  for (i = 2; s = Math.sqrt(number); i++) {
+  // this code is changed from the original one because it was causing infinite loop
+  // when number % i never equals 0
+  for (i = 2, s = Math.sqrt(number); i <= s; i++) {
     if (number % i === 0) {
       return false;
     }
   }
-  return number  1;
-}
+  return number;
+}
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