Can you ace this interview puzzle?

This is a fun interview riddle from Math StackExchange.

Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas!

If you purchase through these links, I may be compensated for purchases made on Amazon. As an Amazon Associate I earn from qualifying purchases. This does not affect the price you pay.

If you purchase through these links, I may be compensated for purchases made on Amazon. As an Amazon Associate I earn from qualifying purchases. This does not affect the price you pay.

Book ratings are from January 2023.

My Books (worldwide links)

My Books (US links)
Mind Your Decisions: Five Book Compilation
A collection of 5 books:
"The Joy of Game Theory" rated 4.3/5 stars on 290 reviews
"The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" rated 4.1/5 stars on 33 reviews
"40 Paradoxes in Logic, Probability, and Game Theory" rated 4.2/5 stars on 54 reviews
"The Best Mental Math Tricks" rated 4.3/5 stars on 116 reviews
"Multiply Numbers By Drawing Lines" rated 4.4/5 stars on 37 reviews

Mind Your Puzzles: Collection Of Volumes 1 To 3
A collection of 3 books:
"Math Puzzles Volume 1" rated 4.4/5 stars on 112 reviews
"Math Puzzles Volume 2" rated 4.2/5 stars on 33 reviews
"Math Puzzles Volume 3" rated 4.2/5 stars on 29 reviews

2017 Shorty Awards Nominee. Mind Your Decisions was nominated in the STEM category (Science, Technology, Engineering, and Math) along with eventual winner Bill Nye; finalists Adam Savage, Dr. Sandra Lee, Simone Giertz, Tim Peake, Unbox Therapy; and other nominees Elon Musk, Gizmoslip, Hope Jahren, Life Noggin, and Nerdwriter.

My Blog

Twitter

Instagram

Merch

Patreon

Press

[anuragguptamr.i.i.t.]

According to Newton's forward interpolation formula, the answer should be 208. Here is the formula created (where, simply b=a+1):


f(a, b) = 8 + 42*(a-3) - 31*(a-4)*(b-4) + (101*(a-4)*(b-4)*(a-5)/6).

[archibaldplum]

The fact that they’re asking questions like that seems like a reason to work somewhere else.

[onealwang]

Guess I'm not getting a job any time soon

[Eduarodi]

What job did they offer? As a lawyer? I mean, if you can convince anyone that the answer is 224, you can win any case.

[ChannelJeffrey]

If this really was an interview, I would say "7×8 is 56, the four people that answered Before me, are wrong, that's obviously why you're looking for new employees"

[Publiclighthouse]

“Congratulations, you got the job. Now, remember the boss takes his coffee with two creams and no sugar and all in-coming calls can reach him through line 4.”

[bryanCJC]

"I'm here for the dog walking job. Just what kind of dogs are these?"

[johnrubber]

I would say that this refers to an exhibition of taxidermy. There are 5 rectangular display cases of dimensions: 3 foot by 4 foot, 4 foot by 5 foot etc. The figure after the = refers to the number of animals in each case. e.g. 3x4 contains 8 toads and 5x6 contains 30 mice. The 7x8 case is the perfect size to display a pair of crocodiles so the answer is 2.

[calholli]

This is exactly how theoretical physicists work.. Lets assume that random 2 is a pattern; then lets assume it has to be a positive integer.. Lets just keep stacking assumptions on top of each other until we feel like quitting.

[WhiteGandalfs]

Since the whole problem has far more degrees of freedom than the presented stipulation, the number of constructions (with literally ANY function whatsoever) that would yield ANY result fitting the presented values could be counted as "infinite". Under those infinity multitude of constructable functions yielding results that satisfy the four presented "result" numbers together with the presented "input" can be ANY amount of instances that as well satisfy the undisclosed result "224" - as well as infinitely more ones that deliver ANY other fifth number.

The takeaway of that nonsense is that the person who made that thing he calls "riddle" has a serious deficit in understanding the principle of "degrees of freedom of systems". I would suggest to strictly avoid entering business partnership with people being at that level of naivety.

[Packaroo]

That is five minutes and 54 seconds of brain cell destruction.

[j.r.]

"Insane Interview Riddle" is actually a good title for this post. What I find mind-boggling is the notion that this kind of question makes for an effective job interview -- for any position. This is not a "see how they think" question; it's a "watch 'em squirm" question. But job interviews as defined by YouTube logic/math channels apparently have little to do with identifying hirable skills. It's a weird, "gotcha" landscape.

[rollnstone]

the answer is 56. 4 incorrect answers don't change that. moving on

[LindyMover]

Basically... you got lucky in guessing that one of the numbers was squared, rather than a log, or a fourier transform of a Huffman compression of "War and Peace."

[nathanmays]

I really dislike the multiplication and equal signs in these riddles. Should be function of or something.

[douglasburnside]

I would not choose to work for a company that thought solving this riddle in some way defined my fitness to do the job.

[squee]

I did the multiplications on the left. Considered the equals sign to be an abstract transformation. Graphed the values on two axis. Called the 4*5=20<=>50 data point an outlier as the other three points can be linearized. Determined the slope between each points to be 1.22, and 1.58. Averaged these to determine the final data point to be approximately 69. 69 final answer!

[CoverBydAn]

In a similar riddle, i saw someone say:

56. The fact that everyone else did it wrong doesnt mean i hv to also be wrong.

Life changing.

[НикитаЧубарь-бф]

I hate such tasks. You can come up with an infinite number of rules that satisfy the given examples.

[kennethforeman]

Since this is a finite length series, the next element can be any number you chose. The challenge is in finding what function justifies that choice. For example, the axb could merely be the x and y coordinates, with functional output being the height. Pick any height at 7x8. Alternatively, we could say that this series is mathematical only. Let (a+b+1) and the answer have a varible multiplier. The multiplier series starts with 1(8/8), 5(50/10), 2.5(30/12), 3.5(49/14) for the given data. Assume the multiplier series is composed of alternating terms of two subseries with those terms related by either addition or subtraction. Then the multiplier series extends as 1, 5, 2.5, 3.5, 4, 2, 5.5, 0.5, ... Hence 7x8 is still 224 but 8x9 is 144 rather than 108 by the pattern found in the video. Without significantly more context, the answer could be anything... The question is more intended to pull out your biases and prior experience, not your ability to find "the" right answer.