Richard's paradox

Richard's paradox arises in the realm of mathematics, particularly in discussions about defining real numbers. It suggests that if we try to list all real numbers in a certain way, we can create a new real number that is not on the list. This new number is constructed by altering the digits of the listed numbers, ensuring it differs in at least one digit from each. This paradox challenges the idea that we can completely enumerate all real numbers, illustrating the complexities and limitations in set theory and the concept of infinity.