Question about double

Question

public class Program
{
public static void main(String[] args) {

double a = 12.3;
double b = 12.0;

double c = a-b;
System.out.println(c);

//output: 0.300000000000007

double d = Math.rint(c*10) / 10;
System.out.println(d);

//output: 0.3

}
}

Why I have to use Math.rint to get 0.3? Has it do to with the type double or with Java?

Answer 1

Not necessarily, usually double precision is used for large numbers only

Answer 2

Thank you for the fast answer. So I should every time use this math method when I use double?

Answer 3

But in my case I don't have large. The code above belongs to my program:
https://code.sololearn.com/c5C9tWQq8Qlm/?ref=app It did'nt worked without using Math.rint ().