printf("%0.6f", number) in c/c++
or
writeln(number:0:6) in pascal

p.s. checkout the other online training/judge website
www.z-trening.com, it has more feedback when you submit a problem

Note that scanf uses "%lf" to read double, but printf must use "%f". It looks like printf with "%lf" does not work on Windows, although it works on Linux.