Symmetric numbers, also known as palindromic numbers, are numbers that remain the same when their digits are reversed. For example, the number 121 reads the same forwards and backwards, making it symmetric. These numbers can be found in various numerical systems, including decimal and binary. Symmetric numbers are often used in mathematics and computer science for various applications, such as coding theory and data validation. They can also appear in puzzles and recreational mathematics, where enthusiasts enjoy finding and exploring these unique numerical patterns.