"Only 1 In 1000 Can Solve" The Viral 1 + 4 = 5 Puzzle. The Correct Answer Explained

This problem was shared on Facebook with the claim that only one in a thousand could figure it out. It went viral and generated over 3 million comments. Here is the problem. If 1 + 4 = 5, 2 + 5 = 12, 3 + 6 = 21, what is 8 + 11 = ? This video presents what many people believe to be the correct answer.

Blog post (text explanation and an extra proof): http://wp.me/p6aMk-4OH

Can you figure this out…only one in a thousand will get it

Posted by Randall Jones on Monday, April 18, 2016

Telegraph coverage
http://www.telegraph.co.uk/education/2016/04/22/this-maths-problem-has-thousands-of-people-baffled-can-you-work/

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28 thoughts on “"Only 1 In 1000 Can Solve" The Viral 1 + 4 = 5 Puzzle. The Correct Answer Explained”

1. MindYourDecisions March 19, 2019 at 5:51 pm

There was an another obscure answer I found in my research that I omitted since I felt it was too complicated. But several people have emailed and commented that they would like this answer to be represented too. So here you go! About 10 people saw this pattern out of 5+ million views this video has gotten. So if you found this pattern, then you're part of a special 1 in 500,000 group!

(By the way, some people have emailed me the answer 52 = (first number) + (line number)*(second number). Note if you use the "missing lines" interpretation, the last line is the 8th line, so you end up with 8 + 8*11 = 96 like the video presented.)

So here's the obscure pattern. The idea is to evaluate the sums in base 10, and then convert the answer into descending number bases 6, 5, 4, etc. line by line. So the pattern is:

1 + 4 = 5 (base 10) = 5 (base 6)

2 + 5 = 7 (base 10) = 5*1 + 2 = 12 (base 5)

3 + 6 = 9 (base 10) = 4*2 + 1 = 21 (base 4)

So if we do the same for the last line, we would need to use base 3 to get:

8 + 11 = 19 (base 10) = 9*2 + 3*0 + 1 = 201 (base 3)

So if you got 201, that's another way people have seen the pattern. It's a bit more involved to explain what is going on, and you can't really reconcile the result with the "missing line" interpretation. But several people did see this pattern.

2. Abdilqadir Dalqamouni March 19, 2019 at 5:51 pm

96

3. #D.J.M# Rúlêz March 19, 2019 at 5:51 pm

I got it as soon as I saw the thumbnail. I didn't even watch the video.
Solution: Add 1 to the second number and multiply it with the first. Tell me if I'm wrong.

4. GOATSNUT March 19, 2019 at 5:51 pm

96

5. Siranee Rattanarag March 19, 2019 at 5:51 pm

40

6. Vasudev Sajeev March 19, 2019 at 5:51 pm

The answer is 12 into 8 as 11 +1 is 12

7. Luke R. March 19, 2019 at 5:51 pm

8 * 11 + 8 = 96

8. Scyonite March 19, 2019 at 5:51 pm

I came to 96 without realizing I was doing a running total. I'll explain: from line 1 to 2 the difference of the right side is +7, from line 2 to 3 it's +9. I noticed both numbers on the left side increased by 1 per line and that the difference remained 3. By seeing 8 + 11 I took this as a validation of the line pattern I saw and extrapolated the addition pattern by adding 11, 13, 15, 17 and 19. Which results in 96. Had I realized the difference in each line was actually the sum of the numbers in the following line I would've identified my answer as a running total. But I only did so when I looked at the video.

TL; DR The funny thing is you can get to the running total result without realizing it's a running total if you don't look further than just the two base patterns.

9. Kaday Kargbo March 19, 2019 at 5:51 pm

( ●
¿
●)

10. Anita Gupta March 19, 2019 at 5:51 pm

52

11. SIDDHARTH GAUTAM March 19, 2019 at 5:51 pm

To all those who feel 96 is not the correct answer, pls study functions and operators in mathematics. Here u r not just guessing the answer but u actually find the function where there are 2 inputs, + sign is an opertor here. Defined as F(a, b) =a*(b+1). Or using opertor a(+) b= a*(b+1).

12. Baby hulk123 March 19, 2019 at 5:51 pm

Calculator said 19 so…..

13. Latika Jagtap March 19, 2019 at 5:51 pm

96
Ya i am coreect
Boring

14. Ruhaan Dheer March 19, 2019 at 5:51 pm

11 multiply by 8 and then +8

15. Ruhaan Dheer March 19, 2019 at 5:51 pm

96

16. امHODA mAN March 19, 2019 at 5:51 pm

٤٠

17. Olga Dumitru March 19, 2019 at 5:51 pm

40

18. Stefan Batory March 19, 2019 at 5:51 pm

It's soo easy 96

19. lucyhydex March 19, 2019 at 5:51 pm

This riddle isn't very good because you have to assume too much and that's just not how math works.

20. Anwar Baloch March 19, 2019 at 5:51 pm

8+11=19

21. mohammad alvee March 19, 2019 at 5:51 pm

40

22. funny video's March 19, 2019 at 5:51 pm

Bachho wale questions h

23. The Killer March 19, 2019 at 5:51 pm

I got it right, but in another way which is
a(b+1)
And it actually worked

24. P1ZZA P13 March 19, 2019 at 5:51 pm

Am I the only one that solved it straight away?

25. sunny PRAKASH March 19, 2019 at 5:51 pm

92 is ans

26. Gnome Ann March 19, 2019 at 5:51 pm

I got 96 as an answer, but oh dear… This problem is an insult to the operation of addition. It would have cool if they gave it some cool symbol, like a ꓃ b, and your goal is to define the operation ꓃. That would definitely be much easier than the confusing use of addition, though.

27. WILD SAFARI March 19, 2019 at 5:51 pm

It can be more simple by the following
1×4+1=5
2×5+2=12
3×6+3=21
8×11+8=96

28. Adi Chauhan March 19, 2019 at 5:51 pm

96