Did you know there is a Titanic Memorial in DC?! If you want to stop by for a picture, it is on the way to Nationals Park, your next checkpoint!
Once you arrive at Nationals Park, find the Home Plate entrance. There is a series of red numbers on the sidewalk. Add them all up and that will give you your final clue! Ignore the 2005 and 2008, they are not on the sidewalk. :-)