The letter 'N' often represents the set of natural numbers in mathematics, which includes all positive integers starting from 1. Natural numbers are fundamental in counting and ordering, making them essential in various mathematical concepts and real-world applications. In addition to its mathematical significance, 'N' can also denote a variable in equations or functions. This versatility allows it to be used in different contexts, such as in algebra or calculus, where it can represent unknown values or quantities that need to be solved for.