Re: rounding problems

[Justin <justin@xxxxxxxxxxxxxxx>]

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 ;