Problem

$2^{15} = 32768$ and the sum of its digits is $3 + 2 + 7 + 6 + 8 = 26$.

What is the sum of the digits of the number $2^{1000}$?

Answer

1366

---

Python

#!/usr/bin/env python
print(sum(int(digit) for digit in str(2**1000)))

---

Ruby

#!/usr/bin/env ruby
puts (2**1000).to_s.each_char.inject(0) {|s,v| s+v.to_i}

---

Haskell

sumDigits ::  Integer -> Integer
sumDigits n = sumDigits' n 0
    where sumDigits' 0 acc = acc
          sumDigits' n acc = sumDigits' (div n 10) (acc + (mod n 10))

main ::  IO ()
main = print $ sumDigits $ 2^1000

---

Java

import java.math.BigInteger;


public final class p016 implements EulerSolution {
	
	public static void main(String[] args) {
		System.out.println(new p016().run());
	}
	
	
	/* 
	 * We implement this solution in a straightforward way with help from BigInteger.
	 */
	public String run() {
		String temp = BigInteger.ONE.shiftLeft(1000).toString();
		int sum = 0;
		for (int i = 0; i < temp.length(); i++)
			sum += temp.charAt(i) - '0';
		return Integer.toString(sum);
	}
	
}

---

Mathematica

(* 
 * We implement this solution in a straightforward way thanks to
 * Mathematica's built-in functions and arbitrary precision integer type.
 *)
Total[IntegerDigits[2^1000]]