Microsoft’s cult of the puzzle…

Borrowed from alles-schlumpf's Flickrstream
Borrowed from alles-schlumpf

Now it’s no secret that I’m obsessed with geeks and the silicon valley. Call me cliche, call me 1990s but for me there’s something mysterious about tech heads who can sit at a computer all day looking at nothing but code and screen

Now it’s no secret that I’m obsessed with geeks and the silicon valley. Call me cliche, call me 1990s but for me there’s something mysterious about tech heads who can sit at a computer all day looking at nothing but code and screen and come up with mind blowing applications, incredible creativity that boggles the mind. So you can imagine my delight when I came across [at a dodgy old charity bookstall] the gem “How would you move Mount Fuji? How the world’s smartest companies select the world’s greatest thinkers”. It basically covers the cult of the puzzle, when big companies like Microsoft used puzzle interviews to determine who was smart, who could think creatively and more importantly, who had the raw genius they were looking for.

So here’s a few  . . .

? Mike and Todd have $21. MIke has $20 more than Todd. How much does each have? You can’t use fractions in the answer.

The basic question is straightforward. You may be tempted to say that Mike has $21 and Todd has $1 but of course that wouldn’t be right because that would add up to $22. The real answer has to be that Mike has $0.50 and Todd has 50c. This is the only answer even if the interviewer insists that there can be no fractions in the answer.

Here the interviewer is wrong [or hiding behind the technicality that cents aren’t fractions] but you’re supposed to stand your ground and defend the answer because that’s life in a big organisation.  Mmm…

How would you weigh a jet plane without using scales?

Some candidates propose to look up the specs online [not allowed]. A traditional version of this riddle asks you how you would weight an elephant without scales. Either way, you can’t put in on scales, you can’t look on the internet and you can’t cut it up into manageable pieces.

The intended answer is that you fly the jet plane onto an aircraft carrier or ferry. You paint a mark on the hull of the ship showing the water level then you remove the jet, the ship will then rise in the water.

Now load the ship with items of a known weight until it sinks exactly at the line you painted on the hull. The total weight of the items will equal that of the jet. Simple really . .

Why are manhole covers round rather than square?

The answer they consider best is that a square cover could fall into a hole  because the diagonal of a square means that should you hold a square near vertically and turn it a little, it falls easily into its hole. A circle has the same diameter in all directions and the slight recess in the lower part of the cover prevents it from ever falling in no matter how it’s held.

Could it also be just be that a round manhole cover is easier to roll when it needs to be transported a short distance?

These brain squeezers are a little abstract for my brain at this time of night so I thought I’d include a few others to test your lateral thinking skills. See if you can get these…

? : A man gets into an elevator in the morning from the 10th floor where his apartment is. He gets in, presses the ground floor, gets out and goes to work. When he comes home he enters the elevator, presses the fifth floor, gets out and then walks up the rest of the way to his apartment. Why?

A : He’s too short to reach the button for the 10th floor so he just goes to the 5th floor and walks the rest of the way up.


? : Someone has been murdered. The police know that it was a lady called Pat but they don’t know what she looks like. They get a tip off about an apartment and they storm the apartment. The police walk in and there are ten people sitting around in the room. They’re all called Pat. The police walk in, without knowing what she looks like and arrest the right Pat instantly. How?

A : All the people called Pat in the room are men. There is only one woman so she must be the right one.


? : There are a hundred people in a cabin on the side of a hill. They’re all dead. What happened?

A : The cabin is an aircraft cabin and they were just in a plane crash.

I won’t relay any more of the puzzles because most of the ones in the book are rather long and complicated. Suffice to say, it’s an excellent read and well worth a look if you can find a copy.

‘How would you move Mount Fuji’ by William Poundstone

1 Comment

  1. They remind me of that old adage: If the black box of a plane is indestructible, why isn’t the whole plane made of the same material.

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