An accounting joke has an employer ask several accountants applying for a job what is one plus one. “Two,” one accountant answers. “Eleven,” another accountant answers. “What do you want it to be?” answers a third accountant, who is hired. The joke has been cited in print since at least 1983.
 
   
26 December 1983, Miami (FL) Herald, “He’s got ideas, but lets others do the translating, business, pg. 7BM:
Anastasios Kyriakides personifies the concept that ideas are money.
(...)
“When I interviewed for an accountant, I asked them what is one plus one,” Kyriakides said.  “If they said two, I didn’t want them. If you want to work for me, you say, ‘What do you want it to be?’”
 
26 December 1989, Philadelphia (PA) Inquirer, “Late Retirement a Pointless Affront to Pa. Constitution” (editorial), pg. A16:
That calls to mind the struggling young accountant who, when asked by a potential client the sum of one plus one, responds, “How much do you want it to be?
     
Google Groups: rec.humor
Wanted: Accountant Jokes
Greg Moritz
5/17/92
(...)
A corporate recruiter hoping to find an accountant to fill a vacancy placed an ad in the local paper.  After interviewing dozens of applicants, the recruiter narrowed his choices down to three possibilities.
 
During the second interview the recruiter decided to ask the candidates a question.  The one who best fielded the question, was the one to be hired.
 
The recruiter asked the question to candidate #1:
“What is one plus one?”
The candidate answered - “that’s easy, it’s two.”
The recruiter responded - “O.K. for today, I’ll call you if I can use you.”

The recruiter asked the question to candidate #2:
“What is one plus one?”
The candidate answered - “Well, do you mean positive one and positive one, or negative one and positive one, or negative one and negative one, or what?  It could be a number of answers.”
The recruiter responded - “O.K. for today, I’ll call you if I can use you.”
 
The recruiter asked the question to candidate #3:
“What is one plus one?”
The candidate answered - “Well, what do you want it to be?”
The recruiter responded - “Your hired!”
   
Google Books
I’m Normal. I AM
By Jeff Myers
Bloomington, IN: AuthorHouse
2006
Pg. 42:
One Plus One
There’s an old joke about a businessman who needs to hire an accountant. The businessman interviews three accountants for the position and asks each one of them the same question, “What is one plus one?” The first interviewee answered the question in the traditional way, stating “Two.” The second, more creative accountant answered “Eleven.” The third accountant gave a rather disturbing answer, “What do you want it to be?”
 
In a world of Enrons, WorldComs, and Tycos, we are no longer amused at the disaster that comes from creative accounting.
 
Google Books
Finding Your Road to Success:
How to Get There Without Getting Lost
By Patrick Daniel
Montréal : PDCA Pub.
2010
Pp. 22-23:
There’s a joke about a client who asks a Chartered Accountant “What does one plus one equal?” The accountant replies, “Whatever you want it to be.”