Question

So, I was trying to do problem # 16 on Project Euler, from http://projecteuler.net if you haven’t seen it. It is as follows:

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?

I am having trouble figuring out how to represent the number 2^1000 in C++. I am guessing there is a trick to this, but I am really stuck. I don’t really want the answer to the problem, I just want to know how to represent that number as a variable, or if perhaps there is a trick, maybe someone could let me know?

Answer 1

Represent it as a string. That means you need to write two pieces of code:

1. You need to write a piece of code to double a number, given that number as a string.

2. You need to write a piece of code to sum the digits of a number represented as a string.

With those two pieces, it’s easy.