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

**So, what’s the answer?**

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They’ll reveal the correct answer tomorrow.

No, it’s not 42.

Tool Reviews, New Tool Previews, Best Tool Picks & Tool Deals Blog

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.

Sections: Awesome & Cool More from: Fein

Marty says

16

John B says

Agreed

bjacob says

I agree with his agreement.

bjacob says

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

Clifford Alloway says

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

fred says

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

fred says

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

fred says

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

Stuart says

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.

bjacob says

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

MichaelHammer says

17

MichaelHammer says

Dag! 25

palm says

The answer is 15. Math order of operation. 10*1 +5.

Wayne R. says

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.

jay dawes says

17

Johnny4 says

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

Will says

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

Johnny4 says

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

Brett says

25

Alexis says

Seconded

Alexis says

Crap nevermind, I just saw what they did, the answer is 15.

Mike says

Yeah i just saw that too. 15 gets my vote

Jag Hundal says

thirded

Jag Hundal says

i stick to 25

Justin says

Count the multitool blades.

Stacey says

Yep

Stacey says

Definitely 25

kdv says

I’m going with 16 as well

Grizz says

25 is the correct answer. Order of operations is multiplication/division before addition/subtraction. The expression is 5 + (2 x 10).

Corey says

17.

Corey says

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👍

Corey says

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

Ewoud says

10+10+10 = 30

10+5+5 =20

5+2+2=9

5+2=7 7×10 = 70

Leo Bauer says

70

Struggleville says

17. 100%

Wayne says

There is a multiple, so 70

Wayne says

Forgot order of operations lol

Doh- 25

Allen Wilson says

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

Harry says

70

Matt S says

15

Matt S says

10+10+10=30

10+5+5=20

5+2+2=9

10+(1*5)=15

csroc says

Yep. Tricksy because I didn’t see the change in the number of blades on my phone screen without looking closely.

Marty says

Ooo didn’t notice the multiplication sign!!

Austin S says

Agreed

Michael Polk says

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 🙂

TonyT says

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

Davin says

It’s 15 guys. Remember order of operations. (PEMDAS)

CraftsmanForever says

25 is the answer

Ryan says

Yep, $25. Multiply the 2×10 then add the 5.

Ryan says

My bad, didn’t notice there’s multiple blades stacked on line 3. Answer is 15.

Tom Magill says

60

sellers says

you are correct

Michael Polk says

And too bad there is no prize lol

Brien says

15

Tom Magill says

Ah… order of operators.

Change mine to 15

Paul Dajewski says

60

Luis says

70

Josh says

15

Willson says

60

And Bob’s your uncle.

There is no spoon.

The cake is a lie.

Craftsman forever says

25 is the answer

Addison says

It’s Fein so infinity! And the HSS cutter is dull.

Tim says

60

Justin sherriff says

10+10+10=30

10+5+5= 20

5+2+2= 9

5+2=7×10= 70

70

Justin sherriff says

60

5+1×10=60

4 blades on line 3 only 1 blade in the riddle

BenV says

15, the multiplication takes precedence over the addition…

Noli says

This guy gets riddles Answers 17 everyone

Nol says

Edit**

It’s 60 ohh man now I’m confused.

Henry says

The answer is 15

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

Brian Harris says

15

Don says

17

Scott Davis says

The answer is 15.

Ryan Rich says

25.

10×2 +5

Don says

Oops 70. Missed the “x” on the last question

PHILIP JOHN says

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.)

Michael says

60!!!!!!!!!

Brett says

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

🙂

ChrisP says

1×5=5. So

10+(1×5)=15

Raoul says

15

Brett says

holy crap now I can’t even add when I can see LOL

15

MacLean says

60

Vards Uzvards says

5+1+10=16

Vards Uzvards says

Scratch the above! 🙂

5+1×10=15

Math is hard!

Scott K says

15. PEMDAS + Pinch to Zoom for the win!

A W says

15.

Doubling the OMT blades is sneaky.

evadman says

10+10+10=30

10+5+5=20

5+(1+1)+(1+1)=9

5+(1*10)=15

Harry Klein says

76

Darth says

17

Darth says

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

Harry says

650

Mike says

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.

andy says

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

Corey says

This may be the best answer lol

Johnny4 says

All the incorrect answers after MattS explanation amuse me.

Louie Orama says

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.

Ryan says

Multiply before dividing. It’s actually this: 5+(1×10)

Lukas says

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.

Alexis says

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

Lukas says

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.

Adam says

15

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

Kurt says

60

Brian A says

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.

Adam spiller says

The answer is 16

Altan says

Was it made in Germany also?!!!

Cary says

17

Rick H says

Answer is 70

Adam says

15

Higgo says

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.

Clint says

25

5+(2*10)

Clint says

15

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

Jerry says

15

OldDominionDIYer says

25

5+2X10

OldDominionDIYer says

Oops there’s only 1 multi-tool blade in the last row so it would be:

(1X10)+5=15

John Fleisher says

15

David C. says

17

David C. says

Edit it is 25, didn’t notice the X in the last row.

David C. says

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

Farid says

15. I assume 15% discount if you buy the combo shown.

Steve says

I’m with Rick H at 70

Steve says

Ok, second try: 60

Craig says

17

Craig says

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

John says

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)

Stuart says

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.

John says

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.

Marcus says

15

David A. says

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).

Robert says

5+ (2×10) = 25

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

John says

Only a single blade in the last equation 😉

Robert says

Huh, thought it was too easy. Sneaky.

Tyler says

25

10+10+10 = 30

10+5+5 = 20

5+1+1+1+1= 9

5+1×10 = 15

Tyler says

Aaaand I typoed the first part of my answer.

G Greene says

15

JMG says

Quite the amusing post…

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

Steve says

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

Steve says

Wait….wrong! 15!

George Gallo says

70, no calculator needed

A=10

B=5

C=2

A+A+A = 30

A+B+B = 20

B+C (7)* A= 70

Dale Ianni says

15

Steve Newman says

15 (multiplication before addition)

Trippy says

60

Matt Shellito says

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.

John says

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

Stuart says

NOPE!

John says

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?

al crespo says

70

The What? says

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?

The What? says

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.

Raoul says

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?

Ben V says

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

ca says

I’m going with 9.

Corey says

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

steve says

25

NCD says

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

Stuart says

If you’re going to be wrong, better by a wild mile than a foot. =)

NCD says

I’ve been wrong before, honestly.lol

Patrick says

I am saying 60.

Grady says

60

Steve says

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.

Cody says

Don’t over think it!!! SIXTY IS THE ANSWERC

John says

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.

glenn says

70.

glenn says

Just rechecked, its 60.

glenn says

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.

Stuart says

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.

glenn says

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.

Stuart says

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

ktash says

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

ChrisP says

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.

Chip says

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

Garrick says

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?

Shawn says

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.

Randy says

70.

Kevin says

70!

Kurt Fehrenbach says

60

TcJ says

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).