“Single’s Inferno 5” Brainy Cast Member Gets Clowned After Viewers Spot Unexpected Fumble

Another unexpected moment from Single’s Inferno 5 is going viral, and this time, it has nothing to do with romance. Contestant Sung Hun is being playfully roasted online after viewers noticed something unusual during his introduction segment.

When Sung Hun first appeared on the show, he introduced himself as a quant trader, immediately piquing viewers’ curiosity. The production also included footage of him standing confidently in front of a whiteboard filled with what appeared to be complex mathematical formulas, reinforcing his finance and data-driven background.

But eagle-eyed viewers decided to take a closer look. Screenshots of the whiteboard quickly circulated online, with netizens attempting to decipher and solve the equation written behind him.

According to online forums, the formula either didn’t compute correctly or contained structural inconsistencies that made it mathematically incorrect.

성훈 이거 수학공식 틀렷다는게 뻘하게웃김 네티즌들 진짜지독하다 pic.twitter.com/d1DS1aRkg6

— 툐끼 (@kkkukkkuu) February 11, 2026

The way netizens were like the math formula is wrong had me cracking up. They’re so intense LOL.

kkkukkuu

As the comment went viral on X too, more people chimed in, correcting him.

Yall brutal lmaoo but yeah matrix multiplication isn’t commutative so the last part is incorrect https://t.co/QW4bW3RVEV

— naufal (@naufxl) February 11, 2026

That's Ordinary Least Squares (OLS) and the answer is correct and if write it in correct way is

B= (X^T X)^{-1} X^T y https://t.co/HbhObQ5yTy

— .MR🥺 (@JooonieIndigo7) February 11, 2026

Some tried solving it for themselves.

이게틀린건가 https://t.co/I9AO4vEjGi pic.twitter.com/j4zRGFhx3B

— 진수성찬 (@injeong49505767) February 11, 2026

Some were more critical.

퀀트 트레이더 맞나?

대학교 3학년때 나도 배운건데

이걸 틀리나?? https://t.co/XOgqMdeu1K

— 일평 (@ilpyung98) February 11, 2026

Are you sure he’s a quant trader? I learned this in my third year of college. How can he get this wrong?

ilpyung98

It remains unclear whether the equation was actually Sung Hun’s own work or simply part of the show’s production design, although he did write on it in the scene. The internet has once again proven that no detail is too small to escape scrutiny!