9 - 3 ÷ 1/3 + 1 = ? The Viral Math Problem in Japan

9 - 3 ÷ 1/3 + 1 = ? The Viral Math Problem in Japan

References:

Thumbnail Credit:

Script:

Hello Everyone and welcome to this weeks Viral Math Problem.
This video went viral in Japan a few months back after the media reported that *ONLY* 60% of 20 year olds could arrive
at the correct answer.
The media was surprised at such a low success rate given that Japanese students do very well in international math tests.
In this video, I will introduce you to this viral problem.
We will try to solve it together and also see why it has been generating so much interest.
So here it is, our Viral Math Problem.
9 - 3 / 1 /3 + 1
I want you to do 2 things, please.
Try to solve the problem WITH and then WITHOUT a calculator.
Once you are done, come back and we will look at the solution together.
Ok, good luck and see you shortly.
Welcome back.
The problem looks pretty straight forward.
It has whole numbers and fractions and 3 basic mathematical operations : Addition, Subtraction and Division.
So let us first try solving it using a calculator.
The problem looks simple so I will use a basic calculator and NOT a scientific one.
So lets start entering the problem into this calculator :
9 minus 3 divided by one third and finally plus 1.
The calculator says 9 is the correct answer.
Ok let me pause for a few seconds.
If you see anything wrong with this answer, please mention it in the comment section.
Now let us try solving the problem again, using a calculator but this time, we will be a bit more patient and analytical.
So let us look at our problem again:
9 - 3 / 1 /3 + 1.
Let us separate this portion and give it our attention.
3 divided by 1/3.
So what does this mean?
Well, bring on the visuals….
Let us imagine we have 3 jars of water.
And we have some plants and each plant needs 1/3 of a jar of water
So how many plants can we water using our 3 jars?
Let us visualise this:
So we have our 3 jar.s And now let us divide each jar into 3 equal parts
as you can see, 1 jar , can , water 3 plants.
So three jars can water 9 plants. right.
So what we are basically seeing is that 3 divided by one third can be written as
3 multiplied by 3 divided by 1 or just 3 multiplied by 3.
Now with this knowledge , let us go back to our problem and change it.
Our problem can also be written as follows
9 - 3 into 3 + 1
Now we can easily solve this ourselves but let us first feed it to the calculator.
We should get the same result as previously, right. Lets check it out…
Hmm. We get one..This is different from our first answer, which was 9.
So why did we get a different answer the first time?
To answer this question, lets quickly revisit the original problem.
So here is our problem once again:
9 - 3 / 1 /3 + 1
When we entered the problem into the calculator for the first time, the calculator did not understand that the fraction one third needed to be grouped
together.
So it calculated the value of 3 / 1 /3 which gave us 1 and which is incorrect.
Let us now tell the calculator to group the 1 third together and see what happens:
As you just saw, the calculator evaluated the 1/3 first as per PEMDAS rules
So we got
9 - 3 / 0.333 + 1
And this results in 1, which is the correct answer.
Did you figure this out?
Please let me know what you thought of this video. I would love to hear from you.
My name is Sanjay and I make thought provoking Math and Science videos.

[funzaAcademy]

This problem went viral a few months back in Japan and was shared and discussed heavily on the internet. Hope you like it. Do not forget to comment please and also like and subscribe.

[lord.d_]

Did you forgot to multiply by the reciprocal of 1/3?

[sanchitmehta]

9-3÷1/3+1
9-3×3+1
=1
Simple, these type of questions I have done in 4 grade or 3 grade

[ghislainmaury]

Here I'll do as my former math teacher told us : "Check/add the invisible parentheses before doing the calcul"

Here 9 - 3÷ 1/3 + 1 = 9 - 3/(1/3) + 1
(fewer risk of error with that new expression)
Then no problem :
9 - 3*3 + 1
9 - 9 + 1
1

[the_life_of_juu]

From bodmas rule i got neg 1 as the answer... hw is it 1... 😓

[ayuumi]

It is a pretty simple problem... like with anything in life.. if you are rushing, you are more likely to make a mistake... so im guessing that is the reason why some people got a wrong answer.

[luciacepriano]

I do not think it is correct to treat "three divided by one third" as if it meant (3/1)/3. That equals 1. But if you try that with 2/6 instead of 1/3 then, (3/2)/6 and 3/2=1.5 and 1.5/6=.25. That is not correct.

[muhammadshahzadfaisal]

9-3÷1/3+1= 9-3X3+1=9-9+1....Here first we will perform addition operation as per BODMAS so it will be 9-10 which is equal to -1. SO correct answer as per me is -1 instead of 1.

[swethathouta]

The answer 9 is wrong and those students were dumb.

[marceliusmartirosianas]

[[[9-3/1/3+1]]]=[[ 9+1+1]= 11 ACADEMIC MARCELIUS MARTIROSIANAS ATRADEJAS expert , Garbes Dakteras./