A mathematician, an economist and an accountant apply for the same job.
The interviewer calls in the mathematician and asks "What do two plus two equal?" The mathematician replies "Four." The interviewer asks "Four, exactly?" The mathematician looks at the interviewer incredulously and says "Yes, four, exactly."
Then the interviewer calls in the economist and asks the same question "What do two plus two equal?" The econmist says "On average, four - give or take ten percent, but on average, four."
Then the interviewer calls in the acountant and poses the same question "What do two plus two equal?" The accountant gets up, locks the door, closes the shade, sits down next to the interviewer and says "What do you want it to equal?"