row is too big

select version()
"PostgreSQL 8.2.19 on i686-pc-linux-gnu, compiled by GCC gcc (Debian
4.3.2-1.1) 4.3.2"

Before you jump down my throat about bad design, this is a reporting
table that is generated based on what the users want to see in their
rows and columns. (I'm basically generating a spreadsheet for the user
to copy and paste and then play with graphing functions)

I have a table with 952 fields one text, one int, all the rest numeric
(no precision or scale defined).
The value of one row is the sum of all the other rows (insert into table
select sum(a),sum(b),sum(c)...)
The values in this case all fit into an integer size, int column is a
sum of all the other columns and is <300,000
The text value is blank ('' not null. When I made it null it took up 16
more bytes)
I am getting an error on inserting the total row:
ERROR: row is too big: size 11436, maximum size 8136

The manual doesn't say exactly how much storage a numeric type uses, but
it seems to me that it is taking up about 12 bytes per field. Does this
make any sense?

Thanks
Sim