+ ## 📺 Watch Now
+
+
+
+
+
+
+ We hope that you found the tutorial video helpful in understanding the loops in javascript, You can refer this notes 📝 for quick revision.
+
+
+ ## 📝 Study Notes
+### Question 1: Sum of all natural numbers from 1 to n
+
+```javascript
+function sumOfNaturalNumber(num){
+ let sum = 0;
+ for(let i=1; i<=num; i++){
+ sum = sum + i;
+ }
+ return sum;
+}
+
+console.log(sumOfNaturalNumber(5)); // 15
+console.log(sumOfNaturalNumber(10)); // 55
+console.log(sumOfNaturalNumber(8)); // 36
+```
+
+### Question 2: Sum of digits of a number
+
+```javascript
+function sumOfDigits(num){
+ let sum = 0;
+ while(num > 0){
+ sum += num%10;
+ num = Math.floor(num / 10);
+ }
+ return sum;
+}
+
+console.log(sumOfDigits(1287)); // 18
+```
+
+### Question 3: Count the number of digits of a number
+
+```javascript
+function countDigits(num){
+ num = Math.abs(num);
+ let count = 0;
+ do {
+ count++;
+ num = Math.floor(num / 10);
+ } while (num > 0);
+ return count;
+}
+
+console.log(countDigits(121)); // 3
+console.log(countDigits(-1211413131)); // 10
+```
+
+### Question 4: Check if a number is palindrome
+
+```javascript
+let isPalindrome = function(x) {
+ let copyNum = x, reverseNum = 0;
+
+ while(copyNum > 0){
+ const lastDigit = copyNum % 10;
+ reverseNum = reverseNum * 10 + lastDigit;
+ copyNum = Math.floor(copyNum / 10);
+ }
+
+ return x === reverseNum;
+};
+
+console.log(isPalindrome(121)); // true
+console.log(isPalindrome(1234)); // false
+```
+
+### Question 5: Find nth Fibonacci number
+The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence,
+such that each number is the sum of the two preceding ones, starting from 0 and 1.
+
+```javascript
+let fib = function(n) {
+ if(n < 2){
+ return n;
+ }
+
+ let prev = 0, curr = 1, next;
+ for(let i=2; i<= n; i++){
+ next = prev + curr;
+ prev = curr;
+ curr = next;
+ }
+ return next;
+};
+
+// Fibonacci Sequence: 0 1 1 2 3 5 8...
+console.log(fib(5)); // 5
+console.log(fib(10)); // 55
+```
+
+### Question 6: Missing Number in an Array
+Given an array nums containing n distinct numbers in the range [0, n],
+return the only number in the range that is missing from the array.
+```javascript
+let missingNumber = function(nums) {
+ let sum = 0;
+ for(let i=0; i nums.length*(nums.length+1)/2 - nums.reduce((acc, num) => num + acc);
+
+console.log(missingNumber([3,0,1])); // 2
+console.log(missingNumber([9,6,4,2,3,5,7,0,1])); // 8
+```
+
+
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