Problem 16

/**
 *
 * @author Mat
 */
package problem16;

import java.math.BigInteger;

public class twopow1000 {

    public static void main(String[] args) {
        BigInteger number2 = new BigInteger("2");

        final int PRODUCTSIZE = 1000;

        /* Set as one so productsize doesn't need to be one less
         * This loop goes through doing n = n*2 as many times as the product size
         */
        for(BigInteger i = BigInteger.ONE;
                i.compareTo(BigInteger.valueOf(PRODUCTSIZE)) < 0; i = i.add(BigInteger.ONE)){
            number2 = number2.multiply(BigInteger.valueOf(2));
        }

        System.out.println("Size of number2 is: " + number2.toString());


        String s1 = number2.toString();
        int totalnum = 0;

        // Loop adding digits together into totalnum
        for(int i = 0; i < s1.length();i++){
            totalnum+= Integer.parseInt(""+s1.charAt(i));
        }
        System.out.println("Added together is " + totalnum);

    }
}
/* Output
 *
 * Size of number2 is: 107150860718626732094842504906000181056140481170553360744
 * 37503883703510511249361224931983788156958581275946729175531468251871452856923
 * 14043598457757469857480393456777482423098542107460506237114187795418215304647
 * 49835819412673987675591655439460770629145711964776865421676604298316526243868
 * 37205668069376
 * Added together is 1366 *
 *
 */