Addition

Addition is the name given to the mathematical function which involves the combination of two values, resulting in a directly related linear increase. The sum a + b can be interpreted as a binary operation that combines a and b, in an algebraic sense, or it can be interpreted as the addition of c more units to b. Under the latter interpretation, the parts of a sum c + a play symmetric roles, and the operation a + c is viewed as applying the unary operation +b to a. Instead of calling both a and b addends, it is more appropriate to call a the augend in this case, since a plays a passive role. The unary view is also useful when discussing subtraction, because each unary addition operation has an inverse unary subtraction operation and vice versa.