Operator Precedence

     ((3 + 4) * 9 - 2 * 3)?

A: It is as though the expression were fully parenthesized as:

     (((3 + 4) * 9) - (2 * 3)) = 57

Q: Why this parenthesization, and not some other one, like:

     ((3 + 4) * (9 - (2 * 3))) = 21 ?

A: Because of the precedence rules of arithmetic:

• + and - have the same precedence,

• * and / have the same precedence, but higher than + and -

• When there are two consecutive operators and one has higher precedence, do that one first.

• Operations within innermost parentheses (if any) are done first.