A recent CNN arti­cle explains well why a grow­ing num­ber of com­pa­nies use brain­teasers and logic puz­zles of a type called “guessti­ma­tions” dur­ing job interviews:

- “Seem­ingly ran­dom ques­tions like these have become com­mon­place in Sil­i­con Val­ley and other tech out­posts, where com­pa­nies aren’t as inter­ested in the cor­rect answer to a tough ques­tion as they are in how a prospec­tive employee might try to solve it. Since busi­nesses today have to be able to react quickly to shift­ing mar­ket dynam­ics, they want more than engi­neers with high IQs and good col­lege tran­scripts. They want peo­ple who can think on their feet.”

What are tech­nol­ogy com­pa­nies (Google, Microsoft, Ama­zon) and con­sult­ing com­pa­nies (McK­in­sey, Boston Con­sult­ing Group, Accen­ture…) look­ing for? They want employ­ees with good so-called Exec­u­tive Func­tions: problem-solving, cog­ni­tive flex­i­bil­ity, plan­ning, work­ing mem­ory, decision-making, even emo­tional self-regulation (don’t try to solve one of these puz­zles while being angry, or stressed out).

Want to try a few? Below you have our Top 7 Guesstimations/ Logic Puz­zles for Brain Challenge:

Please try to GUESS the answers to the ques­tions below based on your own log­i­cal approach. The goal is not to find out (or Google) the right answer, but to 1) iden­tify the logic approach that will help “guessti­mate” an appro­pri­ate range, say + or – 30% of the actual answer, and then 2) com­plete the cal­cu­la­tions (ide­ally men­tally, but you can also take notes) to pro­vide an estimate.

Ready. Set. Go!

1) How many times heav­ier than a mouse is an elephant?.

2) How many fire­fight­ers are there in San Francisco?.

3) How many trees are there in NYC’s Cen­tral Park?.

4) How many shoes have you had in your life?.

5) How many golf balls can fit in a school bus?.

6) In 1999, how were these baby boy names ranked by pop­u­lar­ity: Kevin, Jose, Hugh.

7) What is the weight of a large com­mer­cial airplane?.

The Answer appear below. Again, the key here is to try, plan the steps towards the solu­tion, and do the men­tal cal­cu­la­tions to find a rea­son­able range. That’s the brain chal­lenge. The goal is not to find the pre­cise cor­rect answer.

Answers:

1) Around 150,000. An aver­age ele­phant weighs 4,000 kg on aver­age; an aver­age mouse 25 grams.

2) Around 350 fire­fight­ers on duty on any given day, out of a pool of 1700 fire­fight­ing over­all staff.

3) There are over 26,000 trees (of approx­i­mately 175 species) in the Park.

4) We don’t know (or need to know) how many pairs you have had.

5)  About 500,000, assum­ing the bus is 50 balls high, 50 balls wide, and 200 balls long.
6) Rank­ings of baby boy names in 1999, accord­ing to Social Secu­rity Admin­is­tra­tion: 1. Jose (#30), 2. Kevin (#32), 3. Hugh (#830).

7) For a Boe­ing 747:
– Empty: around 400,000 pounds (lbs), or 181 met­ric tons
– Max­i­mum Take­off Weight: around 825,000 pounds, or 374 met­ric tons
– For con­text, the weight of an empty Hum­mer is 8,600 pounds.

More Con­text on Exec­u­tive Func­tions:
If you want to learn more about what they are, here are some quotes from my Inter­view with neu­ropsy­chol­o­gist Dr. Elkhonon Goldberg:

Alvaro Fer­nan­dez: Please tell us more about what the Frontal Lobes are.

Elkhonon Gold­berg: We researchers typ­i­cally call them the Exec­u­tive Brain. The pre­frontal cor­tex is young by evo­lu­tion­ary terms, and is the brain area crit­i­cal to adapt to new sit­u­a­tions, plan for the future, and self-regulate our actions in order to achieve long-term objec­tives. We could say that that part of the brain, right behind our fore­head, acts as the con­duc­tor of an orches­tra, direct­ing and inte­grat­ing the work of other parts of the brain.

I pro­vide a good exam­ple in The Exec­u­tive Brain book, where I explain how I was able to orga­nize my escape from Rus­sia into the US. Sig­nif­i­cantly, the path­ways that con­nect the frontal lobes with the rest of the brain are slow to mature, reach­ing full oper­a­tional state between ages 18 and 30, or maybe even later. And, given that they are not as hard-wired as other parts of the brain, they are typ­i­cally the first areas to decline.

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Ready for that job inter­view now (on either end of the table)? In case they help, here you have more brain teasers.

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