.. title: HackIM 2013 - Programming 300 WriteUp
.. slug: hackim-2013-programming-300-writeup
.. date: 2013/03/02 05:00:33
.. tags: CTF, nullcon, HackIM, WriteUps 
.. link: 
.. description: WriteUp for Nullcon HackIM CTF Programming 300

**Programming 3 - 300 points**

**Description:** So our folks wanted to work on binomial series but they understood incorrectly so they made a series of this type.
if series is for 10 numbers
::
    
    10/1 + 9/2 + 8/3 ..... 1/10 = 22.218
    round to 2 decimal place = 22.21
    
now they did calculated this series for 31337 numbers can you help these guys in finding the number again.
::

    public class Binomial {
        static final int number=31337; // The binominal value that we are searching for based on the requirements.
        /** * @param args the command line arguments */
        public static void main(String[] args) {
            // TODO code application logic here
            double sum=0; // sum is declared and initialised with the value of zero.
            for(int ctr=1;ctr<=number;ctr++)
            {
                sum=sum+(((number+1)-ctr)/ctr);  // The method of calculation used.
        // e.g.  Term 1: sum=0+(((31337+1)-1)/1),            
        // Term 2: sum=31337+(((31337+1)-2)/2), ...,
        //Term 31337: sum=311180.64640351594+(((31337+1)-31337)/31337)
            }
            System.out.printf("%.2f\n",sum); // Round off to two decimal places.
        }
    }

The flag is: **311180.65**