You know, you should head downhill for a bit. Take the number of that fire truck as you pass it. You'll probably want to take a right at Elon's place. It's a nice drive so keep going, but remember to turn off at the Birth Unit. Once you get back to the top of the hill, feel free to head to the staff car park. But before you turn off, be sure to make a note of how many unknowns there are on the pavement there. Now take all those digits and add 'em together until you're left with one.