Can you solve this brain-teaser shared by a maths professor that’s been melting the minds of folk on Twitter?
At first glance the following question posed by maths professor Anthony Bonato over on Twitter seems to be completely nonsensical. At second and third glance, too, if we’re being completely honest with ourselves.
But it turns out that there is a logically correct answer, so if you’re in the mood for giving your brain a bit of a workout then take a look at this.
Love this one pic.twitter.com/QBY8ZYMwOX
— Anthony Bonato (@Anthony_Bonato) July 14, 2026
Did you get there? First we’ll show some of the incorrect replies.
1.
Easily 2. None of the answers are correct, and 2 is the only one that discards all answers without having another correct, redundant answer like 5 and 6.
— Ashi (@inside_ashi) July 14, 2026
2.
If 4 means “at least one of the above”, then 4 is the correct answer
— booshack (@janothaus) July 14, 2026
3.
6 is the only absolute and the question asks for “correct” which is an absolute, so although 2 is correct it is not absolute because 1 is still an option and therefore unaccounted for if you answer 2
— Jack (@blackridgellc) July 15, 2026
4.
If 2 is true it makes 4 true, which negates 2 which then negates 4, which again makes 2 true, in an infinite loop of toggling.
— Joey (@Fly_Over_Guy) July 15, 2026
If, however, you answered ‘5’ then you can give yourself a clap on the back and take the rest of the day off. You deserve it.
5.
The first four cancel out by logic, therefore 5 is true and 6 is jealous
— What’s This Now (@X_whatsthisnow) July 15, 2026
6.
if 6 is true then 5 is true -> 6 is false
if 1 is true then 2 is true -> 1 is false
1 is false so 3 can not be true -> 3 is false
3 & 1 are false, so if 2 is true then 4 is true. if 4 is true then 2 is true -> 2 & 4 are false
1,2,3,4 are false -> 5 is true.— ᛒᚤᚾᚾL∈ (@Layserguy) July 15, 2026
7.
My brain went crazy trying to go down the list, I kept jumping references. But then I started on 3 and it was pretty easy.
— Kevan MacGee (@kevanmacgee) July 15, 2026
8.
Wow, really cool. So 1 conflicts with 2, 1+2 being false conflicts with 3. So 1,2,3 cannot be true means that 4 cannot be true also. Which makes 5 true, which in turn makes 6 false because 5 and 6 is the same and 6 being true makes 5 false.
So the anwser is 5.— Yuriy Stets (@stainless_code) July 14, 2026
9.
2 and 4 punching it out in my brain for a solid few minutes before I settle on 5.
— Morgan Dorian Trias (parody) (@Morgue_XiiV) July 15, 2026
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