cast numeric with scale and precision to numeric plain

I'm using 8.2.4

Numeric with scale precision always shows the trailing zeros.

Numeric plain only shows numbers after the decimal point that are being
used.

I would like to have the data in my table with scale and precision, but
my views to be cast to numeric without any scale or precision.

However, when I cast a numeric(16,4) to a ::numeric it doesn't cast it.

In order to get the results I want, I have to cast it twice ::double
precision::numeric and then it removes the trailing zeros.

Is there any way to cast directly from numeric with scale and precision
to plain numeric?

example:

create table test(f1 numeric(16,4));

insert into test(f1)values(15),(200.004),(12.4123);
select f1 from test;
15.0000
200.0040
12.4123

select f1::numeric from test
15.0000
200.0040
12.4123

select f1::float::numeric from test
15
200.004
12.4123