It just doing simple mathmetical expression,
For ex -
declare @i int
select @i = -5
select @i*@i
Answer = 25
declare @i int
select @i = 5
select @i*-@i
Answer = -25
declare @i int
select @i = 5
select -@i*-@i
Answer = 25
Mohammad Irfan
http://matespoint.blogspot.com
http://www.irfit.com