Write a program that simulates the decay of a sample that contains 10,000 atoms of radioactive material, where each atom has a 50 percent chance of decaying in a year. The output of your program should show the number of atoms remaining at the end of each year

 import acm.program.*;  
 import acm.util.*;  
 public class atoms extends ConsoleProgram {  
   public void run() {  
        int total = 10000;  
        int count = 0;  
        while (total > 0) {  
             count++;  
             if (total == 10000) {  
                  println("There are " + total + " atoms initially.");  
             }  
             total = (halfMinus(total));  
             println("There are " + total + " atoms at the end of year " + count);  
        }//ends while  
   } //ends run  
   private int halfMinus (int number) {  
        int difference;  
        if (number < 30) {  
              difference = rgen.nextInt(1,3);  
        } else {  
              difference = rgen.nextInt(12,31);  
        }  
        int choice = rgen.nextInt(1,2);  
        if (choice == 1) {  
             number -= difference;  
        } else {  
             number += difference;  
        }  
        number /= 2;  
        return number;  
   }  
   RandomGenerator rgen = new RandomGenerator();  
 }//ends class  

While this does give me the result I'm looking for, I am not satisfied with it 100% of the time. The issue is when it gets down to the lower numbers, sometimes when it hits 2,1 or 0, it will go for a few more rounds. Anyway, this serves its purpose.