Rosenlicht states this consequence as follows: "In a sum or product of several real numbers parentheses can be omitted." (see ita-2-1-5-pg17) In written expressions, parentheses affect the order in which operations are performed. The innermost parenthetical expressions are evaluated first, and parentheses that are at the same level of 'innermost-ness' are evaluated from left to right. Consequently, I presume that this consequence is equivalent to saying that any number of numbers have a unique sum and product. The following material is provided in support of this assertion.