A digital sum is the sum of all of the digits in a number so 214123 = 2+1+4+1+2+3 = 13 - The Tower of Hanoi puzzle involves moving disks in a certain order. What is digital sum of the number of required moves to solve 500000-disk Tower of Hanoi puzzle?

challenge.java

package demoproject;

import java.math.BigInteger;

public class blah {

	public static void main(String[] args) {
		BigInteger big = BigInteger.valueOf(2).pow(500000).subtract(BigInteger.ONE);
		String[] num = big.toString().split("(?!^)");
		int number = 0;
		for (int i = 0; i < num.length; i++) {
			number += Integer.parseInt(num[i]);
			//System.out.println(number);
		}
		System.out.println("cake:"+number); // 677568
	}

}