Numeric Math Functions Oracle PLSQL

SQL>
SQL> select bin_to_num(1,1,1,0) from dual;
BIN_TO_NUM(1,1,1,0)
-------------------
                 14
SQL> select bin_to_num(1,1,1,1) from dual;
BIN_TO_NUM(1,1,1,1)
-------------------
                 15
SQL>