Error while casting to decimal! - response (4) by barani_sachin

Adithya,
    This is the complete expression

sel col1 + POWER( b.col2 , 2 ) * c.col3 AS a25

here col1 & col2 are decimal (12,0) and col3 is integer.
What baffles me is when i tried to cast as decimal i am getting that error whereas i casted it as varchar(here no data loss is possible because i casted it to varchar(100)) and then cast it as decimal its not throwing the error.