# Verification if a number is Palindrome in JavaScript

Let’s say, we have to write a function that takes in a Number and returns a boolean based on the fact whether or not the number is palindrome. One restriction is that we have to do this without converting the number into a string or any other data type.

Palindrome numbers are those numbers which read the same from both backward and forward.

For example −

121
343
12321

Therefore, let’s write the code for this function −

## Example

const isPalindrome = (num) => {
// Finding the appropriate factor to extract the first digit
let factor = 1;
while (num / factor >= 10){
factor *= 10;
}
while (num) {
let first = Math.floor(num / factor);
let last = num % 10;
// If first and last digit not same return false
if (first != last){
return false;
}
// Removing the first and last digit from number
num = Math.floor((num % factor) / 10);
// Reducing factor by a factor of 2 as 2 digits are dropped
factor = factor / 100;
}
return true;
};
console.log(isPalindrome(123241));
console.log(isPalindrome(12321));
console.log(isPalindrome(145232541));
console.log(isPalindrome(1231));

## Output

The output in the console will be −

false
true
true
false

Updated on: 21-Aug-2020

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