Pivot Tables

Hello again ...

I have a question regarding the ability of pivot tables
and since i have not found much information on
calculations based upon information derived from the pivot
table i am seeking help from you guys. Here is the
problem... I have a pivot table set up to give me the
quantity and gross labor cost for that particular item,
that all works fine and dandy. I would also like for the
pivot table to calculate the time duration, the unit
price, and quantity per mason. All of these items are
calculated from one another and stem from the total
quantity and labor cost for a given item. They also
require a third piece of data which is found on another
sheet and that is the day cost for that particular area of
work.

For instance... let say we have 30,000 blocks and they
cost $100,000 in labor.

1 the duration is calculated by the total labor (100,000)
divided by the day cost (located in another sheet and is
found using a vlookup)... the result is the duration

2 the unit price is easy, divide the labor by the number
of units

3 the quantity per mason ... simply the number of block
(30,000) divided by the duration

Granted all of these are very easy calculations to make,
my problem is how do i get the pivot table to make them?
Can a pivot table perform calculations other than those
specifically listed in the Pivot Table Field list?

If you know how to perform simple arithmitic in pivot
tables it would be greatly appreciated if you could pass
that information along to me as it would be a great deal
of help. Of if you know where i can find more information
and do the research myself that would be appreciated as
well.

Thanks,

Scott