"New York Math" joke

A construction site boss was interviewing men for a job, when along came a New Yorker. "I'm not hiring any wise-ass New Yorker," the foreman thought to himself, so he made up a test hoping that the New Yorker wouldn't be able to answer the questions, and he'd be able to refuse him the job without getting into an argument.
"Here's your first question," the foreman said. "Without using numbers, represent the number 9.
"Without numbiz?" the New Yorker says. "Dat's easy," and proceeds to draw three trees.
"What's this?" the boss asks.
"Ain't you got no brains? Tree' n tree n' tree makes nine."
"Fair enough," says the boss.
"Here is your second question. Use the same rules, but this time the number is 99."
The New Yorker stares into space for a while, then picks up the picture that he has just drawn and makes a smudge on each tree. "Dare ya go."
The boss scratches his head and says, "How on earth do you get that to represent 99?"
"Each a da tree's is dirty now! So it's dirty tree,' n dirty tree,' n dirty tree. Dat's 99."
The boss is getting worried he's going to have to hire him, so he says, "Alright, last question. Same rules again, but represent the number 100."
Mr. New York stares into space again, then he picks up the picture again and makes a little mark at the base of each tree, and says, "Dare ya go. A hundred."
The boss looks at the attempt. "You must be nuts if you think that represents a hundred."
The New Yorker leans forward and points to the marks at the tree bases, and says: "A little dog comes along and craps by each tree, so now you've got: dirty tree an' a turd, dirty tree an' a turd, an' dirty tree an' a turd, which makes one hundred. When do I freakin' start?"