# Horse Algebra Goes Viral!

When a math problem goes completely viral on the internet…I sit up and pay attention. This is an absolutely amazing problem to spark a math discussion in  your class. It looks deceptively simple. Let me tell you something…it isn’t! Don’t get overconfident! Take your time and give it a shot right now!

There is an incredibly HUGE chance that you are WRONG…even if you are supremely confident!!

Thousands…literally THOUSANDS of people across the world have been baffled by this simple problem. I’m not talking about just the general population either…I’m talking about MATH TEACHERS, too!!

It’s an example of a super fun way to spark a spirited debate and discussion about math. As people try to justify their answers it leads down wonderful paths to explore.

If you like this way of thinking…taking viral stories and issues from the world around you and using them in class, you are going to absolutely LOVE Instant Relevance by Denis Sheeran (to be clear, the above example is not from the book)! It is our latest book release and it is not only hilarious, but also filled with practical ways to make learning fun and relevant. Many, but not all, of the examples are from math classrooms. It is much more about a mindset, though, as opposed to the math. Always ask, “How can I use that?”

This could be a great way to spark a conversation at the dinner table, too! In fact, that is exactly what we did last night and the results were unbelievable! Total engagement. Total fun. AND…it was all about math!! For more examples of bringing math home in a fun way, check out this TABLE TALK MATH post.

Where would the fun be in that!! If I just let you scroll down and get the answer it takes you off the hook. The fun is in the journey!

But…I will reiterate…YOU ARE PROBABLY WRONG! Don’t look up the answer to this until you have shown it to at least 5 different people (or all of your classes) and you have seen for yourself how outrageously different the answers will be.

It is INSANE!!

Okay…if you get really desperate to know you can beg in the comment section or hit me up on Twitter at @burgessdave.

Remember! This is a problem to be shared and discussed! Some things are WAY more fun when done with others. (Hey! Relax! I’m talking about MATH!)

Let me know how it goes!

Dave

Please note: I reserve the right to delete comments that are offensive or off-topic.

## 69 thoughts on “Horse Algebra Goes Viral!”

1. RG Speigner says:

42

• Dave Burgess says:

Shoot me either a DM at @burgessdave on Twitter or email me at dave@daveburgess.com with your guess!

2. emily edgar says:

42???

3. emily edgar says:

• Dave Burgess says:

To verify you can DM at @burgessdave on Twitter or email me at dave@daveburgess.com with your guess!

4. Bruce says:

Okay, I’m begging. My answer is 21.

• Dave Burgess says:

To verify…Shoot me either a DM at @burgessdave on Twitter or email me at dave@daveburgess.com with your guess!

5. Ann says:

Your Mom did it and I got 22 but I also think it is a one-legged cowboy riding a horse that only has one shoe!

6. rachael postle-brown says:

I’m thinking 21, ….

7. merapp says:

I’ve GOT to know the answer!
Is it 42???? Inquiring minds want to know (as well as a Math teacher who lives in my house).

• Dave Burgess says:

Shoot me either a DM at @burgessdave on Twitter or email me at dave@daveburgess.com with your guess! (But keep working first!)

8. Vickie says:

22.
Easy peasy…love it!

• Dave Burgess says:

Hmmmmmmm. I think you better… Shoot me either a DM at @burgessdave on Twitter or email me at dave@daveburgess.com with your guess!

9. Debbie says:

I am begging! 42?

• Dave Burgess says:

Hahahaha! Shoot me either a DM at @burgessdave on Twitter or email me at dave@daveburgess.com with your guess!

10. Tom Binninger says:

Dave I think the answer is 13

• Dave Burgess says:

Shoot me either a DM at @burgessdave on Twitter or email me at dave@daveburgess.com with your guess! (need to keep working, though!)

11. Kisha says:

• Dave Burgess says:

Shoot me either a DM at @burgessdave on Twitter or email me at dave@daveburgess.com with your guess!

12. Janet Jury says:

Hi Dave, I’m Janet Jury (I actually introduced you when you presented in Syracuse NY last Spring). I’m begging you to HELP me with this. I teach an amazing group of gifted New Visions students at our local BOCES and I love it when I can stump them, especially early on in the school year. On a side note, I read two more of the books you recommended over the summer and LOVED them both. Thank you for helping make teaching so FUN. Oh, one more thing, I loved the branches of government (rope) lesson you shared with us, is that written down anywhere so I can steal it?

• Dave Burgess says:

Hi!! Thanks so much!! Shoot me either a DM at @burgessdave on Twitter or email me at dave@daveburgess.com with your guess!

13. Cathy Koenig says:

14. NIESHA DAVIS says:

18?

15. Darrien Graham says:

48

16. KT says:

17. Camber Talley says:

I want to know!!! Is it 42?

18. John says:

Okay now I see the answer is 22…Cute!

• Dave Burgess says:

Hold on!!! Still one little mathematical hurdle to clear!

19. Jane Beck says:

I think the answer is 21 because of the order of operations.

20. My husband and I say 48 for sure and we both agree.

• Dave Burgess says:

uh oh!! Compare the images in last line with images in lines 2 and 3

21. Mr. Kosal says:

Hi Dave,

We just tackled this problem in my 2nd hour math class and we are CONVINCED!!! … that the answer is 21! Boom!

Mr. Kosal – Wheeler High School

22. Shirlee says:

“22 thoughts on “Horse Goes Viral?” I believe 22 is the correct answer.

• Dave Burgess says:

Hmmmmmm. Think about the math principle embedded in that last line…

23. Jake says:

The answer is 21 because on the last line you have to follow PEMDAS. On the last line, you do multiplication first and the addition.

Right?

24. Jake says:

On the last line you have to follow PEMDAS and do multiplication first and THEN addition

Right?

25. keayra says:

41

• keayra says:

its 21.. math wrong

26. Linda Tisdale says:

13

• Dave Burgess says:

Check that last line again!!

27. Lanelle Faraj says:

28. Z says:

21

29. Carol Bostian says:

OK. I think that I have the answer and have several others from friends. Will you please send the correct answer so we can end the discussion on whose answer is the “right” one?

30. Martin Dillon says:

20 + sqrt of 2 2 variables next to each other with out a operator implies mutiplication.

31. Andy Hostetler says:

It depends. Do you boot the horse before you shoe it or after? It is a bit ambiguous.

32. Chris Walker says:

Diabolical. I think i got it, but it was definitely pretty sneaky.

33. monica says:

LOVE THIS! took me a few to get it…totally gonna use this!

34. Maurice Pudlo says:

h+h+h=30

h+u^2+u^2=18
or
h+uu+uu=18
or
h+(u×u)+(u×u)=18

u^2-b^2=2
or
uu-bb=2
or
(u×u)-(b×b)=2

b+(h×u)=21.4142135624

Someone correct me if I am wrong here “(t)he symbol (⋅), (×), or (∗) between two mathematical expressions, denoting multiplication of the second expression by the first. In certain algebraic notations the sign is suppressed and multiplication is indicated by immediate juxtaposition or contiguity, as in ab.”thus two horse shoes or two boots would not simply be added together but multiplied.

• Dave Burgess says:

Hi, Maurice! You are going deep! My answer differs…but, never trust a history teacher on a math problem!

• Maurice Pudlo says:

Mr. Burgess,
It is my understanding that the most common answer would be 21, then you have my irrational number answer which of course I believe to be correct, there is a rational number answer that differs from mine and is not 21 that rationalized the second images are all exponents…

I never found much joy in math until later in life where I found a practical use for it in a hobby, and again when my children needed help with their own schoolwork.

This problem certainly sparked some renewed interest in working with numbers amongst my own circle of friends.

Thank you,
Maurice

35. Shelley Houston says:

13
I’m going to be at your conference at Tan-Tar-A this month. I’m super excited! 🙂
I came to your page to read some information about the conference and saw this problem. I’m a math teacher and of course had to try to figure it out! 🙂

• Dave Burgess says:

See you soon, Shelley! We can discuss Horse Algebra in MO!

36. Maureen says:

I am so excited to do this one with my class. Just staring equations with my 7th graders and we have been stressing discourse and critical thinking. I LOVE that you aren’t giving the answer. We need to learn to be ok with that and teach our kids that it isn’t about the answer but the effort and discourse! Thanks.

• Dave Burgess says:

Thanks, Maureen!

37. Is the answer 24? I want to use this as my intro with staff tomorrow. Could you share the answer and how it is solved?

DS

• Dave Burgess says:

Hi, Darren…email me at dave@daveburgess.com and we can discuss. But…you still have some work to do!

38. Toby McCullough says:

Has to be 19.

39. Louie Roehl says:

If horse equals 10, 2 boots equals 2, then 1 boot equals one. A pair of horseshoes equals four. So 1 boot equals 1, 1 horse equals 10 so (1 + 10) X 2 = 22

40. Ferenc Bertalan says:

Symbols serve the same function as variables in an algebra problem. This is a series of 1- and 2- step algebra equations. 1 horse has a value of 10. One horseshoe has a value of 2. One boot has a value of 1. Insert these values into the last equation, apply the order of operations correctly, and we get 21.

Right?

41. DANG YOU PEMDAS! Multiply 10×4 THEN add 2!

UGH

42. Daniel says:

The total is 21 one horse times one horse shoe is 20 plus one boot makes 21.

43. Awesome Me says:

h+h+h=30
h+s+s=18
s-b=2
b+h x s=d 1/2
=
10+10+10=30
10+s+s=18
s-b=2
b+10 x s=d 1/2
a=10
=
10+10+10=30
10+4+4=18
4-b=2
b+10 x 4=d 1/2
b=4
=
10+10+10=30
10+4+4=18
4-2=2
2 + 10 x 4=d 1/2
b=2
=
horse=10, shoe=4, boot=2, 1 boot=1, 1 shoe=2,
2 +10 x 4= (4×10)+2=40+2=42 ½= 21

44. Dave Ott says:

It’s clear that horse=10, boot=1 and shoe=2. So depending on the sequence of operations in the last equation, the answer is either 12 or 22. I haven’t taken math for awhile, so don’t know the current rules. I would expect to be guided by parentheses.

• Dave Ott says:

Whoops. Make that 21 or 22.

45. Vincent Porreca says:

13

46. Vincent Porreca says:

change that 22