Banach limit

Banach limit is a way that mathematicians can measure the size of an infinite sequence of numbers. It works by comparing the values of all the numbers in the sequence and seeing if they eventually stay the same. If they do, the size of the sequence is said to be 'convergent', which means it has a Banach limit. For example, if an infinite sequence of numbers was 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,... then the Banach limit of this sequence would be 12.