jGRASP (Java) entering a formula in java

Question

I input this into java and these errors come out. error ")" expected, error not a statement , and error ";" expected. but i do not understand why?

  pent = n(3n-1)/2;

Answer 1

In java this would be

double pent = n * (3.0 * n - 1.0) / 2.0;