Re: rounding problems

As i'm playing around with rounding and the numeric field precision ran
into a odd set of results i don't understand

here is the sql i wrote the first four inserts are calculations we run
everyday and they make sense but if  division is used the results are
not right or am i missing something

create table test_num (
    num1 numeric(20,1),
    num2 numeric(20,2),
    num3 numeric(20,3),
    num4 numeric(20,4),
    num5 numeric(20,5),
    num6 numeric(20,6),
    num7 numeric(20,7),
    num8 numeric(20,8),
    num9 numeric(20,9));

delete from test_num;

insert into test_num values ( (0.70 *1.05), (0.70 *1.05), (0.70 *1.05),
                  (0.70 *1.05), (0.70 *1.05), (0.70 *1.05),
                  (0.70 *1.05), (0.70 *1.05), (0.70 *1.05));

insert into test_num values ( (0.709 *1.05), (0.709 *1.05), (0.709 *1.05),
                  (0.709 *1.05), (0.709 *1.05), (0.709 *1.05),
                  (0.709 *1.05), (0.709 *1.05), (0.709 *1.05));

insert into test_num values( (.5/.03), (.5/.3), (.5/3),
                 (.5/30), (.5/300), (.5/3000),
                 (.5/30000), (.5/30000), (.5/30000));


insert into test_num values( (.5/.03)*.9975, (.5/.3)*.9975, (.5/3)*.9975,
                 (.5/30)*.9975, (.5/300)*.9975, (.5/3000)*.9975,
                 (.5/30000)*.9975, (.5/30000)*.9975, (.5/30000)*.9975);

insert into test_num values( (9*.1),
                 (9*.01),
                 (9*.001),
                 (9*.0001),
                 (9*.00001),
                 (9*.000001),
                 (9*.0000001),
                 (9*.00000001),
                 (9*.000000001));

insert into test_num values ( (9/10),
                  (9/100),
                  (9/1000),
                  (9/10000),
                  (9/100000),
                  (9/1000000),
                  (9/10000000),
                  (9/100000000),
                  (9/1000000000));

insert into test_num values( (1*.1),
                 (1*.01),
                 (1*.001),
                 (1*.0001),
                 (1*.00001),
                 (1*.000001),
                 (1*.0000001),
                 (1*.00000001),
                 (1*.000000001));

insert into test_num values ( (1/10),
                  (1/100),
                  (1/1000),
                  (1/10000),
                  (1/100000),
                  (1/1000000),
                  (1/10000000),
                  (1/100000000),
                  (1/1000000000));

select * from test_num ;