ToolGuyd

Tool Reviews, New Tool Previews, Best Tool Guides, Tool Deals, and More!

ToolGuyd > Awesome & Cool > Fein Tools Math Riddle

Fein Tools Math Riddle

174 Comments

If you buy something through our links, ToolGuyd might earn an affiliate commission.

Fein USA Tools Math Puzzle Challenge

Fein US posted a math riddle to their Instagram channel, shown above.

So, what’s the answer?

Advertisement

They’ll reveal the correct answer tomorrow.

No, it’s not 42.

Related posts:

No related posts.

174 Comments

        • No I don’t. I just realized the last one has multiplication. 60.

          Reply

          • I had to put my glasses on and when I did it looks that 60 is correct…

        • If you consider:

          A= tool
          B= battery
          C= blade

          3A=30 or A=10
          1A+2B=20 so B=5
          1B+4C=9 so C=1

          A+B+C = 5+1+10 = 16

          But if you consider the tool as having a battery that is considered separately – then the equations look like this:

          3(A+B) =30
          1(A+B) +2B = 20
          B+4C = 9

          so from the first equation A=10-B
          substituting into the second equation:
          10-B+B+2B= 20 or B = 10 and then A =0
          Then if 10+4C=9 = C= -0.25
          So in this scenario
          10 + 0 +(-0.25) = 9.75

          Reply

          • Forget what I wrote above

            Should have looked at the last line with multiplication sign.

            Case 1 >> B + C x A = 5+1 x 6 = 60

            Case 2 >> 10 + 0.25 x 0 = 0

          • Case 2 should have been >> 10.25 x (0+10) = 102.5

          • Since A + B is constant in all instances, appearing paired together, it can be considered a single variable, D.

            Whilst there is enough to solve for A, if you consider that the tool is described as A + B, you don’t need to.

            If you sub in B = 10 – A into the second equation, you get:

            A + 3B =20
            A + 30 – 3A = 20
            10 = 2A
            A = 5
            B = 5

            Same as if A+B = 10, or D = 10.

            Considering the bare tool as separate from the battery-equipped tool just makes more work.

      • No I don’t. I just realized the last one has multiplication. 60.

        Reply

      • You’re the first one (here, anyway) to get the math right. Winner! Of what, I don’t know, but your teachers should be proud too.

        Reply

    • The problem included some observational and order of operations subtleties which can easily trip you up.

      List of incorrect answers and why:
      16 – did not notice the multiplication symbol
      25 – did not notice the single blade
      17 – missed both single blade and X
      60 – incorrect math adds before multiplying
      70 – incorrect math and missed the single blade

      Reply

    • Yep,10 for the supercut,5 for a battery and one blade equals 1 so it’s 16.

      Reply

      • Incredible. After all the explanations how can you possibly still think the answer is 16?

        Reply

    • Immediately realize that while I spotted the trick, I applied it wrong in my final step haha I rescind my previous answer and second Marty?

      Reply

      • And still messed up pemdas. Jesus, point taken, Stuart haha

        Reply

    • Hey guys, there’s only one correct answer. It’s all in the details and correct order of math.
      Look at the scrapers, it’s:
      2 scrapers + 2 scrapers = 4
      So:
      1 scraper = 1
      On the last line, multiplication trumps addition in the correct hierarchy of math operations. So, last line is:
      (5) + (1×10) = 15 Final answer

      Reply

  8. The correct answer is 15. I am sure a lot of you will come up with different answers but I will explain to you why this one is correct…tomorrow 🙂

    Reply

    • Yup, that’s what I got…order of operations and count the number of multi-tool blades.

      Reply

  16. 60

    And Bob’s your uncle.
    There is no spoon.
    The cake is a lie.

    Reply

  20. 10+10+10=30
    10+5+5= 20
    5+2+2= 9
    5+2=7×10= 70

    70

    Reply

  21. The answer is 15

    Thank you Mr. Towne (my HS math teacher)!

    Reply

  26. Its 15.

    It would only work out to 60 2 other ways… if it was dewalt or Milwaukee and then I would say give me 60 ( more better tool.)

    Reply

  28. Had to go to the actual computer to see the number of blades everyone is talking about (tablet + old eyes = ahhhh crap I’m wrong….)

    10 + (1×5) = 16
    mumble mumble mumble
    🙂

    Reply

    • Changing to 16 now that i see 2 blades on the 3rd line amd only 1 on the 4th.

      Reply

  40. The whole 2 blades vs 1 is kind of cheating on the trick. I never noticed till I saw someone mention in it and I zoomed in. Small detail on small screens like that is hard to see. 15, the order of operations trick gets people every time.

    Reply

  41. The correct answer is in dollars, and the number is frighteningly high.

    Reply

  42. All the incorrect answers after MattS explanation amuse me.

    Reply

  43. I’m going with 60 as well… First line tells you that the Oscillating Tool is 10. Second line tells you that the battery is 5. Third tells you that each blade is 1. So it is 5+1=6 x 10 = 60.

    Reply

  44. 15 if you do it the meme math way. I’m going to argue that there isn’t enough information. 3 equations with 4 unknowns. The single Fein and double Fein blades should be treated as separate variables. If I were to say that W=10 would you assume that V=5 just because a W looks like two Vs? Probably not.

    Reply

    • If W = 10 we have no way of knowing V, but one could make a strong argument for U = 5

      Reply

      • Well I’m just going by the appearance because that’s what we’re doing in this Fein riddle. I still don’t agree if we go by the name of the variable. Letters weren’t named with algebra in mind.

        Reply

  45. 15
    5+1*10. Multiplication always comes before addition unless there are parentheses. Therefore, 10*1=10, then 10+5=15

    Reply

  47. The answer is a lot of people are bad at basic math.

    Or if you’re smart enough to get the right answer (15) you are to smart to pay Fein prices.

    Reply

  53. Wow! I would not let a majority of you do work on my house 🙂 Our contract would have to have a lot of verbiage re: who’s responsible for the cost of material shortages/overages.

    Reply

  55. 15

    Sorry, poor eyesight, did not see the bunched up blades.

    Reply

  58. Oops there’s only 1 multi-tool blade in the last row so it would be:
    (1X10)+5=15

    Reply

      • Crap, it 15. Too hard to see the multiple blades on a phone.

        Reply

  64. Sorry 70-Didn’t notice multiplication in last step

    3x = 30 so x = 10
    x + 2y = 20 so 10 + 2y = 20 so y = 5
    y + 2z = 9 so 2z= 4 so z = 2

    (y + z)x =70

    Reply

  65. This is funny or sad, not sure which.
    America’s education system at its finest.
    Obeying the rules of mathematics,
    5 + (1 x 10) =
    15.

    As of 100+ comments roughly 1/4 of you gave the actual answer (not counting agreeing comments)

    Reply

    • Gradeschool math gets buried under decades of disuse.

      In high school and college-level math, habitual use of parentheses makes remembering PEMDAS redundant.

      The definition of the derivative is: limit as h-> 0 of ( f(x+h) – f(x) )/h. I had to look that up. I can tell you the derivative of ax^2 + bx + c, or other simplistic functions like that. But anything more advanced? Poof.

      Use it or lose it.

      How do you solve for x in a quadratic equation? Do you remember what y = ax^2 + bx + c looks like graphed out?
      y= mx + b. What’s m? What’s b?

      Use it or lose it. Nobody should feel bad about getting a different answer. Getting tricked by the multiplication sign or the number of accessories… that’s different. =P

      If you used control-F to count how many instances of “15,” a number of those are in x:15 timestamps.

      Reply

      • True on the control-F, but the timestamps with 15 also get included. I see 32 answers with 15 as of this timeline but that still requires going through each of them to weed out other uses of 15 in the webpage. Ahh, how tools can help but also not help.

        As others have said the ‘x’ and single blade in the last equation tripped up a lot of people more than bad math.

        Reply

  67. It’s 15.

    Lots of people initially missed the “x” in the last line on their first read-through and thought it was a “+” (I did), and lots of us missed the change in number of blades between the 3rd and 4th lines (I did too).

    Reply

  68. 5+ (2×10) = 25

    Far as I remember, you multiply whatever you can first, then you add.

    Reply

  71. Quite the amusing post…

    I like the reference to the Hitchhiker’s Guide there.

    Reply

  72. Dang, it’s sneaky. 55….look closely at pics and remember order of operations.

    Reply

  73. 70, no calculator needed

    A=10
    B=5
    C=2

    A+A+A = 30
    A+B+B = 20
    B+C (7)* A= 70

    Reply

  77. Guys it is 15. (1×5)+10

    (1) blade =1 (1)battery=5 (1) tool=10

    Order of operation multiply divide add subtract.

    Come on my 3rd grade daughter just nailed this. I helped with what numbers should be where but she got the answer of 15.

    Reply

  78. I just have to say: With answers like that how did America develop as well as it did over the last 200 years ???

    16 is correct.

    One tool $10
    One battery $5
    One cutter $1

    Reply

  79. For practice answer this: If the electric locomotive is travelling North from NY, NY to Albany, NY at 60mph which way will the smoke blow?

    Reply

  81. It’s either 15 or 60. If you go by order of mathematical operations you get 15. But there’s no mention of that applying to this equation. I got 2 different calculators that gave 2 different answers. So does this mean that I can buy 3 fein oscillators for $30? Or 1 oscillator and 2 batteries for $20? Is that what they’re putting down to pick up? Or is this some sort of bs that they’re trying pull?

    Reply

  82. I don’t mean to jump off topic, but has anyone ever heard of parkside tools. This LIDL store recently opened up the street, which I’ve never heard of, and they have Parkside power tools for unheard of prices.

    Reply

    • I’ve heard Lidl is coming and supposedly do what Aldi does but even better. Both are German I think. What town is it in?

      Reply

  83. Computers never lie:

    ‘Maths.exe’ (CLR v4.0.30319: Maths.exe):

    a = 10
    b = 5
    c = 1

    a + a + a = 30
    a + b + b = 20
    b + (c*2) + (c*2) = 9

    b + c * a = 15

    Reply

  85. I screwed it up twice, early. And it’s making me feel less stupid reading all of the insistently wrong answers even after the entire thing has been explained multiple times. Read 10 comments and you’ll probably see the answer 15 explainy, so how is it still being argued against actually mathematics? It’s okay to be wrong, not so much fo be willingly and defensively wrong lol

    Reply

  87. I think the answer is 600 , but I’m not sure. It’s either that or something else.

    Reply

  90. Nothing Fein sells is cheap so I think a tool, battery, and blade is like $329 minus the charger for $263 divided by the percentage the marketer kicks in, times the square root of probability makes it about $764 . . . or maybe a little more.

    Reply

    • Thanks for playing but wrong.

      The correct answer of 15 has been said over and over and shown why it is correct many times (it’s called MATH), so how people keep coming up with wrong answers is mindblowing or mindnumbing.

      Reply

      • Hmm. Just checked out the answer. Its been quite a while since I left school but I don’t recall being taught that the order of calculation is based on the assumption of brackets being there, where they are clearly not.

        Reply

        • You don’t remember PEMDAS, the order of operations rule?

          Please excuse my dear aunt sally.

          Parentheses
          Exponents
          Multiplication and division
          Addition and subtraction

          So if you have 1 + 2 x 3, the answer is 7, and not 9.

          In more elaborate math, there is greater care to adding parentheses. But in their absense, the order of operations is clear.

          Reply

          • I went to school in Australia so there is possibly a difference, but I genuinely don’t recall any rules that assume there are parentheses. I have always done calculations in order except when there are parentheses to indicate otherwise.

            However, its been 42 years since I left school, so I have forgotten a lot of stuff, lol.

          • If it helps, Wikipedia says that in Australia you use: “BODMAS meaning Brackets, Order, Division/Multiplication, Addition/Subtraction.”

  93. Well, it’s 15. But hard to believe a Fein tool would be that cheap 😉

    Reply

  94. It’s 16,478,135,618.
    I enlarged the image and printed it out on 120 sheets of paper and the counted the pixels with a sharpie and an abacus. Sorry it has taken so long to give you the correct answer but my first attemp was rained out and I had to start from the beginnng.

    Reply

  95. I don’t have time to read the whole thread .
    I used a value of 5 for the battery ,and the tool..2 for multi blades.
    So 2 batteries 10p,1 tool 5p,+1p for single blade 5+5+5+1=16

    Reply

  96. Assuming that Fein wants a numerical answer, I got 17 until I read that there was a Multiplier, then I got 70, until I read there was only one blade in the final equation, so I got 60, until read (and remembered) that multipliers are done before additions. then got 15. So I wrong, wrong, wrong, and then right.

    How come 2 wrongs don’t make a right… but, 3 lefts do?

    Reply

  97. 10+10+10=30
    10+5+5=20
    5+2+2=9
    5+1*10=15
    In the absence of parenthesis, multiply/divide first and then add/subtract.

    Reply

  101. It’s undefined. The number represented by two blades is 2; however, it’s not shown that the number represented by one blade is 1. You can assume that, but the math doesn’t show it.

    For example, the symbol “99” (two nines) does not represent a number that is twice as big as the number represented by the symbol “9” (one nine).

    Reply

Leave a Reply to sellers Cancel reply

Your email address will not be published. Required fields are marked *