Money

I' m trying to perform some simple arithmetic with a field datatype,
money.

For example, select part_id, cost from parts; gives the id and cost
in dollars...
select part_id, cost+1.00 from parts; ....adds $1.00 to
displayed cost.
select part_id, cost*2 from parts; produces an error message...
"There is no operator '*' for types money.....retype this query using
an explicit cast or.....define the operator using CREATE OPERATOR."

If I examine the list of operators using \do, there are any number of
them shown for *, money, int2, float4, etc.

Question 1: Is this a list of existing oeprators or a list of
permitted ones that I have to create?

Question 2: I can't figure out haw to use the CAST :: ....Any
hints?

Again, TIA to one and all.

.......Bill Sneed....Prospect, Maine......