multiple identical calc and function in single query

I have a query which includes the same calculation and function call
multiple times.

Is the calculation and function call evaluated one time or as many times
as it is in the query?

Example:

326/getdisplayconversionmultiplebypn(pnid) is in this query 6 times. How
many times is it evaluated?

select pnid, (326/getdisplayconversionmultiplebypn(pnid)) + case when
coalesce(mpq,0)=0 then 0 else
mpq-((326/getdisplayconversionmultiplebypn(pnid)) % mpq)end as qty,
case when not translatempq then
(326/getdisplayconversionmultiplebypn(pnid)) + case when
coalesce(mpq,0)=0 then 0 else
mpq-((326/getdisplayconversionmultiplebypn(pnid)) % mpq)end
else ((326/getdisplayconversionmultiplebypn(pnid)) + case when
coalesce(mpq,0)=0 then 0 else
mpq-((326/getdisplayconversionmultiplebypn(pnid)) % mpq)end)/mpq end as
mpqqty
from manufacturerpartpn a
inner join leadstatemfgparts b on a.partid=b.partid and
a.manufacturerid=b.manufacturerid
where compatibilitygradeid in (50,100,200) and lifecycleid not
in (-400,-500)
and a.parentid is null and a.PartID=1108 and leadstateid = any
('{1,3}')
and leadstateid <> case when lfbcount>0 then 4 else -1 end
and leadstateid <> case when lpbcount>0 then 2 else -1 end