Yesterday I posed five questions that technology and other leading companies pose their candidates in job interviews.

As promised here are the answers:

Question One

The interviewer writes six numbers on the room’s whiteboard: 10, 9, 60, 90, 70, 66. The question is, what number comes next in the series?

This is not a maths question. Spell out the numbers in plain English, which gives you the following: ten nine sixty ninety seventy sixty-six. The numbers are in order of how many letters are in their names. Ten is not the only number you can spell with three letters. There’s also one, two and six. Nine is not the only four-letter number; there’s zero, four and five. This is a list of the largest numbers that can be spelled in a given number of letters.

What number comes next? It should have nine letters in it (not counting a possible hyphen) and should be the largest nine-letter number. Play around with it and you’ll probably come up with ninety-six. It doesn’t look like you can get anything above 100, because that would start “one hundred” requiring 10 letters and upwards.

At many of these companies, the one and only correct answer is 96. At Google, 96 is considered to be an acceptable answer. A better response is 10,000,000,000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000, 000,000,000. Aka “one googol”.

That’s not the best answer, though. The preferred response is 100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000 or ‘Ten googol’.

Question Two

You and your next-door neighbour are holding car-boot sales on the same day at the same place. Both of you plan to sell the same item. You plan to put your item on sale for £100. The neighbour is going to put his on sale for £40. The items are in identical condition. What do you do, assuming that you’re not on especially friendly terms with this neighbour?

The bit about not being on especially friendly terms should tell you that a strategic response is expected. The friendly solution is to pull the neighbour aside and say, “You’re throwing money away by offering it for £40.” But this plan is not considered an especially good answer. Suppose the big spender finds two identical items on sale for £100. He’s equally likely to choose either one, and the other may go unsold.

You simply want the neighbour’s item off the market. You might offer to pay the neighbour not to market his item. A better answer is simpler: buy the neighbour’s item. He’ll be pleased to sell his item immediately. He’s not likely to be offended or to raise the price. You can haggle, like any other buyer, and may get it for less than £40. Why should you want his item? When you put something on sale for £100, you hope to make a decent profit, compensating for the time you’ve invested in selling it and factoring in the chance that it won’t sell. Anything that diminishes the chance of your item’s selling in effect costs you a significant fraction of that £100.

Question Three

Some applicants are given a test in which they have to count the number of times a given letter appears, upper case or lower case, in a paragraph. It’s a lot harder than it looks. (Don’t believe it? Count the hs in this paragraph. There are 15, and hardly anyone gets all of them.)

Question Four

You’re locked in a pitch-black, empty room with bare walls and no electric lights. You’ve got a book of matches, a box of tacks and a candle. How would you attach the candle to the wall for a light?

The best answer: empty the box of tacks. Take the box top, turn it upside down and tack it to the wall. The box top projects out like a little drawer. Then put a tack to attach the candle to the box’s bottom. The tack’s point, projecting through the box bottom, serves as a pricket. Finally, slide the box bottom into the box top on the wall. The nested top and bottom will be sturdier than either alone, and safely support the weight of the candle.

Question Five

Why are manhole covers round?”

Answer: because round manhole covers, unlike their square counterparts, can’t fall in the hole.

So what do these questions prove? I’m not really sure. I guess it has a lot to do with the sorts of jobs on offer which I presume at tech companies is software related. I’m just pleased I’m not interviewing soon. I only got number 2 correct.

How did you do?

Answers from A Guardian Article and William Poundstone’s book ‘Are You Smart Enough To Work At Google?’

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