A great challenge. A correct answer explained by mathematician. Thank You for watching. The best support for me is to click the like button below the video. Thank You!
This new school crap is pure nonsense. I agree with you. The simple order of operations gets you to the real answer not shown - It’s 120. This five factorial garbage is nonsense.
@@tommybotts Perhaps you didn't understand my joke ? 120 is the right answer here, yes, which is equal to 1*2*3*4*5 = 5! 120! = 1*2*3*4*5*6*7*...*107*108*109*110 and this is areally really big number. That exlamation mark makes a big difference.
@@gerardjlaw I know: statistics, probability, analysis in general - all kinds of series, especially in approximations of functions... It's everywhere. I was asking one of the many that share that they have never heard of factorial why they do it.
It’s probably related to people not knowing what a factorial is, if I showed my parents this they’d likely have chosen A. I did it right getting 120 but not seeing it I almost swapped my answer to A but then remembered 5! Means 5 x 4 x3 x 2 x1.
@@jayewrite1256 But your parents would have been right to choose 70! As geralsilaw said above "This isn't really a maths problem. It's an entirely confected ambiguity, created by - and for - small-minded pedants who think that the cretinous 'BODMAS' rule gives them some kind of superior mathematical insight. In reality, no one who uses mathematical calculations for any kind of actual purpose relies on arcane - and disputed - rules of precedence; we use parentheses. (Source: my first degree was in physics & astronomy and I had a career in engineering.)".
WHY OH DEAR? Just because you have been in a job of some sort that required this information don't hold yourself so superior. The vast majority of jobs don't use anything like it so people don't remember useless information, they remember the stuff they need, no "OH DEAR required!
This is NOT a math problem. It is an obscurely written problem problem. PEDMAS is a fairly recent convention, not a "law" of mathematics. There are other conventions and one set of parentheses makes the statement clear. In a word problem (or a real life problem) no such ambiguity would exist. Yes factorials were taught but in a career in engineering I never saw them used. It is a pointless way to test two useless conventions at the same time.
PEMDAS, Fairly recent since about the 1950s. After a long career in Nuclear Engineering and Operations and Computer Network Systems Engineering, I still remembered FACTORIALS and saw the answer. And no, I never heard of PEMDAS until I started doing these puzzles but we were taught the order of PEMDAS but we did use bracket and parentheses to define the operational order..
This isn't really a maths problem. It's an entirely confected ambiguity, created by - and for - small-minded pedants who think that the cretinous 'BODMAS' rule gives them some kind of superior mathematical insight. In reality, _no one_ who uses mathematical calculations for any kind of actual purpose relies on arcane - and disputed - rules of precedence; we use parentheses. (Source: my first degree was in physics & astronomy and I had a career in engineering.)
@@kingalfred3902 No. The only time that shit is used in marking is in trivial tests early on in school. It doesn't even figure in qualifications for applying to university.
Never worked with Factorials, didn't even know they existed prior to this video. Even so, I got [B] because the other two were wrong and assuming the person posing the question actually knew what they were doing, the only answer left was [B] and must therfore be the correct one. This question is a sneaky double whammy because it's NOT just about getting the correct answer, it is also about testing if you know and will properly apply the PEMDAS rules while testing your knowledge of Factorials. In my case, the question FAILS in its second goal because I didn't know anything about factorials and just reasoned out the correct answer anyway. "I don't know what that 5! means but the other two are wrong so that must be correct".
I took -beginning- algebra in high school and again in college. I knew the answer was 120. BUT I didn't learn about factorials until later, when studying statistics. This was decades ago, so maybe things have changed. But in my day, a beginning algebra student wouldn't know what 5! was.
@@grahammcfadyenhill9555 we had a permutations and combinatorics module that went with algebra. But I recall learning what it meant maybe in grade 8 math (?) might have just been the teacher...
In high school and college, I used algebra to get a good grade in the algebra class and move on to geometry and trig. Now geometry and trig, those were very useful to me in my careers as a broadcast engineer and a mechanical inspector and quality engineer. Math is a very useful real-life skill if your real life requires math!
I don' t remember factorials from math, 50 years ago. so I've learnt something new today. I chose 120 as an answer. since that possibility wasn't there I was curious for the explanation.
Man Alive! You complete parentheses first. Order of operation always takes precedence. Do all division and multiplication from left to right. Then do addition and subtraction from left to right. The answer to the above question is 120.
I Don’t know why people insist on writing mathematical expressions in an ambiguous form, other than trying to trick students. My eighth grade algebra teacher always said that parenthesis and brackets remove doubt, and make the math expression clear. In this case, write the expression clearly and everyone will get the correct solution. It is funny (or appealing) how many “teachers” try to be tricky or cute. Gothcha,
@@odonnelly46 Thanks for the reply. If the mathematical expression is NOT ambiguous, the why does the poster almost brag that 96% will get it wrong? Looks like many people were either never taught the PEMDAS convention or forgot it. That being the case, then parenthesis remove ambiguity. This is just a simple test to see if one understands or remembers PEMDAS. BTW it is not an equation (no = sign), just a mathematical expression.
Some instructors insist on writing a problem on one line, also. There is no reason not to write a division on 2 lines, literally putting the numerator over the divisor. It's amazing how much that simplifies the process, and how much it clarifies the meaning of the work intended to be done.
@@larrystuder6378 Yes, I agree. It begs the question as to when does it stop being instructional and begins to be just tricky. Math should be clear and unambiguous.
Reminds me of a riddle from a long time ago. I forget the actual numbers being used, but it went along the lines: I was once asked another way to write 120. When I yelled "5!" no one believed me!
Use of brackets eliminates ambiguity from problem for those who are far removed from processing conventions ... a simple way to reduce errors and increase reliability of results across users.
This is the first time I've ever even heard of factorials. Up to the beginning of 1968, when I dropped Math for Ancient History, we were not only not taught this principle, but it never appeared in any exams. It makes me feel like somebody changed all the rules about math just to confuse older people. Probably a Sheldon Cooper.
@@JohnSmith-zw8vpMy Math education was in the old Math, beginning in 1958 and First Grade. We learned things by rote and constant repeating tables over and over and over again. We started out writing on slates, and now 65 years later I'm using a computer. Just imagine how much change will have occurred 65 years from now. That's if the Human Race doesn't get so smart they manage to bypass themselves with AI technology.
@@glengreen362 In MegaMan X (1993) Dr Light warned of the disastrous results there would be if the first rule of robotics (A robot must never harm a human being) were broken by any sort of AI.
Left school 50 years ago and have never heard of factorials, but equally even though working in the aircraft industry in various positions since then I NEVER at any time needed them in any way shape or form so is it really needed now ?
@@menmustchangebeforekingdoms well you certainly don't need them to read the bible however that is not to say there are no occasions' they are needed in certain applications of academia and technology.
@menmustchangebeforekingdoms Wow! You really know your Bible! Did you just use your biblical acumin to deflect your ignorance of math? That's just good bible-ing right there! You must be a hoot at parties! Do another one. Give me a verse dismissing my sarcastic comment!😂
Math is the only science where they can change the process rules. This is the reason that children learn to hate math in elementary school. Everyone can add, subtract, multiple, divide and find the square root. Insert parentheses and everyone will get the correct answer.
I learned about factorials from friends in grade school. BTW - multiplication and division should be treated as a single item in the list, as should addition and subtraction. In situations where people may make mistakes, pour on the parentheses...
In Germany we say Punktrechnung vor Strichrechnung wich means point calculation before line calculation. Point calculation is multiplication and division. Line calculation is addition and subtraction.
I knew the answer was 120, but I am not familiar with factorials. That concept was definitely not taugh at my secondary school in England in the 1950s.
At what point in the school system is ! as a factorial taught. I went through high school algebra 1 and 2, geometry, trig and advanced math (1969), and college algebra 1 and 2 and I had never seen a ! used in math until last week when I saw another RU-vid video using it.
120---Parentheses first, exponentiation, then followed by division(or multiplication) which ever comes first[right to left], then addition or subtraction[right to left] are the orders of computation. Also, 5! works because 5!=5x4x3x2x1=120
Well done KiwiGirl. You are right. This is just a simple sum and the answer is 75. However 96% of the people responding on here have got the wrong answer because they don't know that 90+60 divided by 2 is 75. Isn't that extraordinary!
Making my guess at just 0:30 into the video: 5! is the answer, because of the order of operations rule, aka PEMDAS. 5! is 5 factorial, or 5 x 4 x 3 x 2 x 1 = 120. Following PEMDAS, there are no Parentheses or Exponents, Multiplication and Division happen simulaneously, so 60/2=30, and then Addition and Subtraction take place to wrap things up, so 90+30=120.
Pretty sure I had factorials on the SAT 55 years ago, back before they adjusted the curve for the mentally challenged. This is quite easily solved by taking into account Sherlock Holmes' maxim, "When you've eliminated the impossible, whatever remains, no matter how unlikely, is the solution". FWIW, you can't solve qiestions involving odds, probabiliy, combinations and permutations, etc.,without knowing about factorials. Gratefully remembering all the cool stuff my 8th grade math teacher taught us.
@@aday1637 An exact science? But multiple choice tests are mostly about Psychology, which is a soft (read: sham) science. An 'exact' mathematical test question would give you space to answer the question and to show your work. But multiple-choice tests prevail because the underlying rationale for the examining process is to provide an index of how students will deal with uncertainties coming at them. Remember: The Dream of Reason produces monsters. - Francisco Goya (1799)
A previous video instructs that you should commence the procedure indicated on the left! That being the case we should add 90 to 60 and divide the total by 2 which equals 75. This example does not use that approach at all and is confusing at best!
Only start from the left if the signs are equal. (×÷) (+-) the signs in brackets are equal so if you have multiplication and division then the one furthest left is calculated first. We didn't have equal signs here so we just go straight to division first.
@@FerdinandPerez-my8xk That is illogical. Division does not take precedence and it a nonsense to say so. Let me give you an example using this same sum to illustrate this. Lets say 2 people are picking apples. and one picks 90 and the other picks 60 and they agree that they are going to divide the total they pick equally between them. The sum would be presented exactly as shown in the video as 90 + 60 divided by 2. How can the answer to this sum be anything except 75???
@@proteus4301 Division does not take precedence and it a nonsense to say so. Let me give you an example using this same sum to illustrate this. Lets say 2 people are picking apples. and one picks 90 and the other picks 60 and they agree that they are going to divide the total they pick equally between them. The sum would be presented exactly as shown in the video as 90 + 60 divided by 2. How can the answer to this sum be anything except 75???
Well thankyou for answering a question I have had since leaving school in 1972. Why was I so useless at Maths? I worked this out as a simple piece of mental arithmetic: 90 plus 60 equals 150. Divide this by 2 and you have 75. Remember Occam's Razor: All things being equal the simplest answer is usually correct. Why put all that "working out" on paper????? Utterly stupid.
How useful is this in our every day life when you need to know where you money goes and the bills you need to pay. Young people have no idea how that math works! The true math.
i see you've used the factorized version of works! Since 5! = 1x2x3x4x5 = 120 we would factorialize works! into w x wo x wor x works. This is true, true sentence math! (m x ma x mat x math)
As it's written, 75 is the answer. But all the wise arses, with their heads up their arses, would naturally be able to find at least a dozen 'correct' answers to this riveting trivia. They just make it up as they go along. It has zero connection with day to day living. As in budgeting one's money, work, trave, keeping one's personal space clean and organized. Just a lot smart arse, pretentious "crapola", IMO!
As an Application Developer I have to admit I don't always remember the rules. I know I can use parenthesis to ensure I'm getting a calculation to do what I want in the right order. By instinct I went the right direction and remembered the factorial to check my answer. The built in computer language assistants will check me now on having an unnecessary parenthesis. That is a good thing because it keeps me from getting lazy.
If you had a deck of 52 cards and you wanted to calculate how many ways those cards could be arranged, then you multiply 52 x 51 x 50 x 49… Or, you can just calculate 52!.
The answer is actually 120. You have to incorporate PEMDAS to the equation. 90+60÷2= You have to do division 1st due to the order of operations, and 60÷2=30. 90+30= 120. The answer is 120.
90 + 60 = 150 divide 150 X 2 and you get the answer of 75. How can it be different than a)? (FYI ... I graduated in 1995 ... Did Math really change that much in 28.65 years?)
This clot doesn't know what he is talking about. Every primary school child is familiar with the expression BODMAS. Consequently division comes before addition. In other words 90 + 30 = 120. But apparently 5 factorial is the correct answer. Really. It seems to have escaped him that it is exactly the same answer as applying the old rule of division before addition. Not only that, but he doesn't even explain how 5 factorial has any relevance. He just plucked it out of thin air.
@@jimbo43ohara51 AGREE!!! NEVER heard of '5 factorial' when I went to grammar school back in the 60s. BODMAS ruled and it took me about 5 secs to get the correct answer of 120.
I don't remember being taught about PEMDAS or BODMAS in Grammar / Secondary school in the UK (11 years - 17 years), and I was hopeless at maths / math. Factorials I learnt about only 10 minutes ago.
no wonder kids can't add. I have no idea what he is on about, and sorry, I have no idea how he got to 13...my answer was 75, as in, 90+60=150, divided by 2 = 75. Where the rest of it came from, I have no idea --then again I learned my math as arithmetic in the lower grades when 1+1 equaled 2. no factorials, no strange answers and six sheets of paper to perform simple tasks. My friend's son got through math with a B+ and he has no clue h ow many quarters are in a dollar or how to multiply simple problems. I watched a woman at the local (and very small) post office a few weeks ago adding up 10 cent stamps (I ordered ten) 10 10 10 10 all the way down the paper, add 'em up, carry the 1, and yep, that will be a dollar. she also checked her work to be sure she was right.
You make some interesting observations, however your basic arithmetic is flawed. Going left to right gets 75, but going left to right is wrong. Division comes before addition. To get the correct answer going left to right the equation would have to be written as 90 + (60/2) which you would read as 90 plus 30.
@@AshleyReynolds-vc6ly That is BS! Tell me what would 90 apples plus 60 apples divided by two people would be? And how would you write that down except as 90+60 divided by 2?
@@dacorum8053You would write that as (90+60) divided by 2, which is the same as writing 150 divided by 2 = 75. Order of operations is paranthesis first, then division and multiplication before addition and substraction. Therefore, writing it as 90+60 divided by 2 the order of operations is parenthesis first but in this case there are no brackets, then division 60/2 = 30 then addition 90 + 30 = 120. If it was written as (90+60) divided by 2, then order of operations is parenthesis first (90+60)=150 then division 150/2 = 75 which works for your apples example.
@@AshleyReynolds-vc6ly Thanks but in the absence of brackets you do sums like this in the order they are given and multiplication or division do not take any precedence unless you make that clear with brackets. Thus for the answer to be 120, this should be written as 90 + (60/2). That makes it clear that the 60 is to be divided by 2 and not 90+60. Maths should be clear and simple to understand and but the guy doing the video is just an idiot who gets it all wrong.
@@dacorum8053No, order of operations always comes before left to right. Your example of 90+(60/2)=120 is correct, and is another way of writing the original sum 90+60 divided by 2 = 120 or 90+60/2=120. To get an answer of 75 it needs to be written as (90+60)/2=75. If you search 'order of operations' you will find a number of websites that explain it. It is sometimes written as an acronym, BODMAS or PEMDAS, to help you remember: Brackets/Parentheses first, then Order/Exponents, then Division/Multiplication, then Addition/Subtraction. Many people default to reading a sum simply from left to right, but that is incorrect. Try it on a calculator as it is written, 90+60 divided by 2, then hit = and see what answer it gives. For basic arithmetic, if we all used brackets then we could just simply go left to right, but mathematics is far more complex than just basic arithmetic. The bloke in the video is not an idiot and he is not wrong.
The 75 answer is an answer that the brain might jump to when you first see the puzzle but sometimes deeper observation and thought is required. After doing these puzzles for month, I just noticed that it is NOT "BRAIN LOGIC" but "BRIAN LOGIC" !!! Sometimes we just see what we expect to see.
@@stevesmith291 No, they taught you wrong! Tell me what would 90 apples plus 60 apples divided by two people would be? The answer is clearly 75. And how would you write that down except as 90+60 divided by 2?
@@rael5469 No, they taught you wrong! Tell me what would 90 apples plus 60 apples divided by two people would be? The answer is clearly 75. And how would you write that down except as 90+60 divided by 2?
No. That is the answer you get if you go strictly left to right, but doing it that way is wrong. Division first, then addition is the correct order. 60 divided by 2 = 30, 90 + 30 = 120.
I don't agree, I have always been taught to do the multiplication and division first and if you do it that way the answer is 120. I just put this equation into my calculator and, it comes up with the same answer 120. So what's going on?
I took advanced algebra in college and never came across the ! sign in math, ever. Not even once. And I went to a very well known college. So this is some sort of made up trick problem that really is anyone's "guess". Of course 120 is the answer not 5!. Why not 6* or 8^? Let's just make it up as we go?
So if I typed this into a calculator I'd have to change the order of the sum simply because a bunch of abbreviations say they need to be done in that order? If that's the case EVERY sum written needs to be re written to remove this kind of mistake. The other problem is in primary school maths 75 would probably be the correct answer so it's a fucked up set of ideas.
Lets get real and basic. If you have 90 marbles in a jar and you add 60 more , you then have 150 marbles in the jar. Remove half of them (divide by two) you now have 75 marbles in the jar. PEMDAS is wrong. How did we ever get to the moon with this logic?
I want you to go get 150 of something easy to handle. Put 90 of that something in a container. Now add 60 more to the container. Now you have 150 items in your container. Now remove 50% of the items which is 75 items. Now count what is still in your container. You will find there is 75 items in it. This is basic arithmetic. I agree that PEMDAS is a thing but doesn't work in all instances.@@DiamondDon19
oh ...and you are right ..?....While the whole World Education system uses PEMDAS....!!!......What has marbles got to do with this....Just a thought ......you got all your marbles ...???
Factorials need not be introduced in this simple equation. The only reasoning here is following the Pemdas rule... Done. The factorials will just confuse many or perhaps introduce common core math principles which become even more obtuse.... Just remember KISS ( not the band ) Keep It Simple Stupid... The goal to any solution is rationalising which is the most direct path to solving the riddle. Here its division before addition... The choice of solutions offered are designed to lead anyone astray, if you're going to introduce a problem in this manner than one must reveal that the solution to this equation may not be revealed on this page ..
96% of people couldn't do this problem in 1880 ... 1770 ... 1000 ... In the area that would become New Enland, the common man believed in Devil Stones. He would clear his field of stones each spring to plant, and then each winter frost would heave stones from below. They really believed that Satan (and his lessor demons) placed them there each year to torment them. we'll be ok ...
What a load of crap if we have 2 pens of sheep 90 in one 60 in the other put them in one pen we have 150 sheep we take half each we both get 75 sheep no wonder young people have to use a calculator
That would be written as (90+60) divided by 2 = 75. But if you write it as 90 + 60 divided by 2 the answer is 120. Order of operations takes precedence over left to right. Brackets first, then division/multiplication, then addition/subtraction.
Tricking students with concepts they haven't been introduced to yet is not teaching, it's tricking students, which is neither productive nor conducive to learning.
Guess a lot of people don’t look at these question as perhaps being a bit tricky - meaning doing division before addition and realizing that 120 isn’t directly offered as an answer choice, I’d have thought most would look at 5! as being just a sneaky way of restating 120….
The factorial 5 probably tripped many viewers up. And, of course without the factorial explanation symbol, most would have (correctly) answered that a), b) and c) didn't provide the correct answer and so the answer must have been 120. Lesson: Read the questions AND any answer choices provided thoroughly! 😁
For those of us who never could grok algebra, the answer is 75 - because of the sequence. Anyway, majority rules! Sorta Kinda . . . . Thank you for the video which was great fun. P.S. Don't run this one by 'the Donald' ! Might lead to big trouble in Duckburg . . . . etc, etc. etc.
It’s all About sequence. Is it 90 + 60 / 2 or 90 + 30. Thats a learned skill based on a predefined order rule. The algebraic formula notation doesnt define the order rule. It can only be solved “correctly” based on an external assumption.
I have never heard of 'factorials' till this guy mentioned it and I looked it up. Seems like quite a few others have not got a clue about it either. Must be a secret code......
It's not difficult, it just has the answer in a ridiculous format. Why would anyone solve a problem (which requires a number as its answer), but then convert that number into a factorial? You essentially have to choose which two are equivalent, rather than solve!
How can be right? Division does not take precedence and it a nonsense to say so. Let me give you an example using this same sum to illustrate this. Lets say 2 people are picking apples. and one picks 90 and the other picks 60 and they agree that they are going to divide the total they pick equally between them. The sum would be presented exactly as shown in the video as 90 + 60 divided by 2. How can the answer to this sum be anything except 75???
Fascinating, I think most people here would have heard of PEMDAS at some point and would have come to the answer of 120. But given that most people don't know what 5! means, they will generally pick an answer they know to be wrong then an answer they do not understand. Even if process of elimination says the other two are definitely wrong therefor 5! must be the correct answer. That probably says a lot about us.
Pemdas doesn't deal with divisions very well. The answer relies on whether the division sign implies the existence of a division line, giving two possible answers, and confounding Facebook users into arguing, debating, and fighting over the answer over hundreds of responses. In other words, there is no correct answer.
It is total rubbish. Division does not take precedence and it a nonsense to say so. Let me give you an example using this same sum to illustrate this. Lets say 2 people are picking apples. and one picks 90 and the other picks 60 and they agree that they are going to divide the total they pick equally between them. The sum would be presented exactly as shown in the video as 90 + 60 divided by 2. How can the answer to this sum be anything except 75???
Whether you knew about factorials or not only B could be the answer(based on the options given). Even using basic algebra one knew options A and C were definitely 100% NOT correct so one could only go with option C as 1 of the three answers supplied must be correct. Having eliminated options A and C option B had to be the correct answer. Simple really even for one nearly 80 year old.
Most people haven't done much about factorials in maths, mine go back to A level days in the early 1970s.. One example of using factorials is the UK lottery, it has 58 numbers, you pick 6 of them. I was told the odds of winning are 58!/(52! X 6!), so winning it has odds in the tens, if not hundreds, of millions to one. Anybody know if this is correct?
Sounds about right. (58*57*56*55*54*53)/(6*5*4*3*2)=58*19*7*11*9*53= 40,475,358:1 after dividing by common factors so about 40 million to 1, because the order of the numbers is not important
The answer is (Screaming at the top of my lungs...) F I V E !!!!!! Because screaming "FIVE!" at the top of your lungs creates a sound at 120 decibels, which is the same thing as 120. Or something like that.
