Multiply a number by n values in a for loop in Java

I have:

salary = 2000;
n= salary/200 = 10 //number of loops;
contribution = 0.1, 0.2, 0.3, 0.4...;

I need to make a for loop that gets the sum of salary x contribution as:

salary x contribution1 = 500x0.1
salary x contribution2 = 500x0.2
...etc...

this is a method of my class:

public static double pensionContribution(double salary) {
		
		
	double n = salary/200;
	int n_round = (int) Math.floor(n);
		
	int start = 1;
	List<Integer> n_list = IntStream.rangeClosed(start, n_round)
			    .boxed().collect(Collectors.toList());
		
		
	double counter = 0.1;
		
	for (int i = 0; i < n_list.size(); i++) {
           System.out.println(n_list.get((int) (salary*counter)));
                 
    }
		counter = counter + 0.1;
		//need the sum of all values of (salary*counter)
		
	return n_round;
			
	}

Thanks!

you can use this loop:

for(int i = 0;i < [times to loop];i++){

     resultofmultiplication = (salary*counter)
     sum = sum + resultofmultiplication
     counter = counter + 0.1

}
return sum;

you will get all the results from the multiplications summed. idk why you need a list but this will give you the sum of the multiplications

For each n in the list you need to calculate salaryn0.1 and sum all.
This can be done in one stream:

public static double pensionContribution(double salary) {
    double n = salary/200;
    int n_round = (int) Math.floor(n);
	return IntStream.rangeClosed(1, n_round).mapToDouble(i->salary*i*0.1).sum();
}