An Irishman applied for a job on a construction site, but the foreman wouldn't hire him until he passed a simple maths test.

Here is your first question, the foreman said. "Without using numbers, represent the number 9."
"Without numbers?" The Irishman says, "Dat is easy," and proceeded to draw three trees.

"What's this?" the boss asked.
"Ave you got no brain? Tree and tree and tree make nine," said the Irishman.

"Fair enough," said the boss. 
 
"Here's your second question. Use the same rules, but this time the number is 99."
The Irishman stared into space for a while, then picked up the picture that he has just drawn and made a smudge on each tree. "Ere you go"

The boss scratched his head and said, "How on earth do you get that to represent 99?"

"Each of da trees is dirty now. So, it's dirty tree, and dirty tree, and dirty tree. Dat is 99."

The boss was getting worried that he's going to actually have to hire this Irishman, so he said, 
 
"All right, last question. Same rules again, but represent the number 100."
The Irishman stared into space some more, then he picked up the picture again and made a little mark at the base of each tree and says, "Ere you go. One hundred."

The boss looked at the attempt. "You must be nuts if you think that represents a hundred!"

The Irishman leaned forward and pointed to the marks at the base of each tree and said, "A little dog came along and crapped by each tree. So now you got dirty tree and a turd, dirty tree and a turd, and dirty tree and a turd, which makes one hundred."

'So, when do I start?'

H/T "The Pops" who emailed us@mostlysafeforwork.com with this little gem.