Addition is the process of combining two or more quantities together. It is a mathematical operation denoted by the symbol “+”, which is referred to as the plus sign. In verbal expressions, the terms “plus,” “sum,” “total,” “more than” and “increased by” are synonymous with addition.
For example, placing three marbles with four marbles yields a sum of seven marbles. This is written in mathematical notation as “3 + 4 = 7” and is read as “three plus four equals seven."
Addition can also signify the joining of physical and abstract quantities, such as negative numbers, irrational numbers, variables, fractions, vectors, functions and others.