Oracle PL/SQL Tutorial/Introduction/Arithmetic operator

The normal rules of arithmetic operator precedence apply in SQL

The normal rules of arithmetic operator precedence apply in SQL:

multiplication and division are performed first.

followed by addition and subtraction.

If operators of the same precedence are used, they are performed from left to right.

SQL> SELECT 10 * 12 / 3 - 1 FROM dual;
 10*12/3-1
----------
        39
SQL>

Use parentheses () to specify the order of execution for the operators

SQL>
SQL> SELECT 10 * (12 / 3 - 1) FROM dual;
10*(12/3-1)
-----------
         30
SQL>