Reverse of a number

Palindrome numbers and its reverse are the same

The reverse of a number is a mathematical method to obtain from a number another written in the opposite way to the first.

For example, the reverse of 1234 is 4321.

Method

Given a positive integer $x$, the integer which has the same digits in the reverse order is:

$10^{\lfloor {\log }_{10}x\rfloor }x-99\sum _{k=1}^{\lfloor {\log }_{10}x\rfloor }\lfloor 10^{-k}x\rfloor 10^{\lfloor {\log }_{10}x\rfloor -k}$

Applications

Obtaining the reverse of a number is useful to predict if a number is Lychrel or not.