If a variable takes values which are more and more close to a finite number , then we say that approaches written as ). * If values of come closer to but are always greater than , then we say that approaches form right (). * If values of come closer to but are always less than , then approaches from left () . The concept of a limit is essentially what separates the field of calculus, and analysis in general, from other fields of mathematics such as geometry or algebra. The concept of a limit may apply to: * Limit of a function * Limit of a sequence * Limit of a series