to_number('123') : TO_NUMBER « Conversion Functions « Oracle PL/SQL Tutorial

SQL>
SQL>
SQL> select 123
  2  ,      to_char(123)
  3  ,      to_char(123,'$09999.99')
  4  ,      to_number('123')
  5  from   dual;

       123 TO_ TO_CHAR(12 TO_NUMBER('123')
---------- --- ---------- ----------------
       123 123  $00123.00              123

SQL>

15.8.TO_NUMBER
	15.8.1.	TO_NUMBER(x [, format]) converts x to a number.
	15.8.2.	Convert the string 97.13 to a number using TO_NUMBER() and then adds 25.5 to that number
	15.8.3.	Converts the string -$12,345.67 to a number, passing the format string $99,999.99 to TO_NUMBER()
	15.8.4.	to_number('123')