Tina Orooji

http://projecteuler.net/index.php?section=problems&id=6

# Project Euler - Problem 6 (http://projecteuler.net/index.php?section=problems&id=6)

# Generate the sum of squares and square of sums using summation formulas, then
# subtract.
def p6():
    n = 100
    squareOfSum = ((n*(n+1))/2)**2
    sumOfSquares = (n*(n+1)*(2*n+1))/6

    print squareOfSum - sumOfSquares

http://projecteuler.net/index.php?section=problems&id=13

This one was tricky until I Googled “java big integer” and found out about Java’s BigInteger, lol. It made the problem much simpler. After I got the answer I saw some posts on the forum saying that only the sum of the first 11-15 (it varied) digits were needed, but I’m not fully convinced of that yet. The other digits could lead to values being “carried over”, which will impact the total sum. So, I still stand by my solution… for now ) I’ll keep thinking about the other solution and see if I’m able to convince myself one way or the other.

	/* Project Euler - Problem 13 (http://projecteuler.net/index.php?section=problems&id=13)
	 *
	 * Saved the numbers to a file for neatness.  Then just read from the file and used
	 * Java's BigInteger.
	 */
	public static void p13(){
		String line = null;
		BigInteger sum = BigInteger.ZERO;

		try{
			BufferedReader input = new BufferedReader (new FileReader("numbers.txt"));

			while((line = input.readLine()) != null)
				sum = sum.add(new BigInteger(line));
		}
		catch(IOException e){e.printStackTrace();}

		System.out.println(sum.toString().substring(0,10));
	}