Microsoft is legendary for having a challenging interview process. Candidates are typically tested both socially and mentally, with questions designed to either knock the applicant off his or her game, or provide a window into the applicant’s thought processes. SellsBrothers.com has a great compilation of notable Microsoft interview questions. Some of my favorites are listed below. For the full list and some horror stories about Microsoft interviews, check out the site.

Microsoft Interview Questions

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Riddles

• Why is a manhole cover round?
• You’ve got someone working for you for seven days and a gold bar to pay them.
  The gold bar is segmented into seven connected pieces. You must give them a
  piece of gold at the end of every day. If you are only allowed to make two
  breaks in the gold bar, how do you pay your worker?
• Imagine a disk spinning like a record player turn table. Half of the disk is
  black and the other is white. Assume you have an unlimited number of color
  sensors. How many sensors would you have to place around the disk to determine
  the direction the disk is spinning? Where would they be placed?
• Suppose you had 8 billiard balls, and one of them was slightly heavier, but the
  only way to tell was by putting it on a scale against another. What’s the
  fewest number of times you’d have to use the scale to find the heavier ball?
• Imagine you are standing in front of a mirror, facing it. Raise your left hand.
  Raise your right hand. Look at your reflection. When you raise your left hand
  your reflection raises what appears to be his right hand. But when you tilt
  your head up, your reflection does too, and does not appear to tilt his/her
  head down. Why is it that the mirror appears to reverse left and right, but not
  up and down?
• You have a bucket of jelly beans. Some are red, some are blue, and some green.
  With your eyes closed, pick out 2 of a like color. How many do you have to grab
  to be sure you have 2 of the same?

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Applications

• How can computer technology be integrated in an elevator system for a hundred
  story office building? How do you optimize for availability? How would
  variation of traffic over a typical work week or floor or time of day affect
  this?
• What is the difference between an Ethernet Address and an IP address?

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Thinkers

• How are M&Ms made?
• If you had a clock with lots of moving mechanical parts, you took it apart
  piece by piece without keeping track of the method of how it was disassembled,
  then you put it back together and discovered that 3 important parts were not
  included; how would you go about reassembling the clock?
• If you are going to receive an award in 5 years, what is it for and who is the
  audience?
• Suppose you go home, enter your house/apartment, hit the light switch, and
  nothing happens - no light floods the room. What exactly, in order, are the
  steps you would take in determining what the problem was?