What is the lower bound of 9?

The lower bound of a number, such as 9, refers to the smallest value that is considered in a particular context or set. In the case of the real numbers, the lower bound of 9 is simply 9 itself, as there are no numbers smaller than 9 that can still be considered within that context. If discussing a set of numbers, the lower bound would be the greatest number that is less than or equal to all numbers in that set.