函数返回值报错问题ora-06503

一个函数

create or replace function get_tax_1(p_salary number)
return number as
tax_salary number;
V_NUMBER  NUMBER;
begin
    tax_salary := p_salary-FLOOR(p_salary);
    IF tax_salary <= 0.3 THEN
      V_NUMBER :=FLOOR(p_salary);
      RETURN V_NUMBER;
    end if;
    IF tax_salary >= 0.4 AND tax_salary <= 0.7 THEN
      SELECT (CEIL(p_salary) + FLOOR(p_salary)) / 2 INTO V_NUMBER FROM DUAL;
      return V_NUMBER;
    end if;
    IF tax_salary >= 0.8 THEN
      V_NUMBER :=CEIL(p_salary);
      return V_NUMBER;
    end if;
end get_tax_1;create or replace function get_tax_1(p_s