Make a for loop method with if statements return the correct "return" without array?

I am doing some java exercises and I am trying to make a method that counts to 100 and prints the number each time the for loop "loops".
The exception is that it will print "Fizz" when the number is divisible by 3 and "Buzz" when the number is divisible by 5. Now, I have three return types in my method that is gonna return a String. However, the error says I do not return a value. I am aware that I have to make it return a String outside the for loop but I am having some trouble figuring out how I should get to return the value that I want.
I am also aware that I could use arrays or even arrayList to fix this problem but I think its possible without that and I would like to try doing so.

Any help would be very appreciated!

Here is the code:

package etcOvaningar;

public class ovning1 {

    public static String fizz ="Fizz!";
    public static String buzz ="Buzz!";

    public static String countDown(){
    for (int number = 0; number < 100; number++){
        if (number%3 == 0){
            return fizz;
        }
        else if (number%5 == 0){
            return buzz;
        }
        else
            return String.valueOf(number);
    }
           //I need to insert a return here I suppose, but I want the correct return from the if and else //statements
    }

    public static void main(String[] args){
    }
}