Street smart mathematics

A Houston construction boss was interviewing men for a job, when along came a Louisiana Cajun. "You gotta pass my test first", he told the applicant.
"Here's your first question."

"Without using numbers represent the number 9."
"Without numbers?" the Cajun says. "Dat's easy," and proceeds to draw 3 trees.
"What's this?" the foreman asks.
"Well, tree and tree and tree make nine," says the Cajun.

"Fair enough," replies the foreman. "Here is your second question. Use the same rules, but this time the number is 99."
The Cajun stares into space for a while, then picks up the picture of the three trees and makes a smudge on each tree. "Ere you go."
The boss scratches his head and says, "How on earth do you get that to represent 99?"

"Each of da trees is dirty now! So dirty tree and dirty tree and dirty tree. Dat is 99!"
"All right. Last question. Same rules again, but represent the number 100."
The Cajun stares into space again, then picks up the picture again and makes a little mark at the base of each tree, and says, "Ere you go. One hundred!"
The foreman looks at the attempt. "How in the world does this represent a hundred?"

The Cajun leans forward and points to the marks at the tree bases, and says,
"A little dog come along and crap by each tree, so now you've got dirty tree and a turd and dirty tree and a turd and dirty tree and turd, and dat make one 'undred. So when do I start work?"