“Single’s Inferno 5” Intelligent Cast Member Mocked After Viewers Notice Surprising Mistake

Sung Hun is facing unexpected backlash — but not for love. The Single’s Inferno 5 contestant’s math skills are under fire.

The controversy began when Sung Hun introduced himself as a quant trader. The show cut to a whiteboard filled with complex equations behind him, suggesting serious finance skills.

Soon after, eagle-eyed viewers zoomed in on the formulas. Screenshots spread online with netizens pointing out errors and inconsistencies in the math.

Some called out the incorrect matrix multiplication. Others said the whole formula didn’t compute.

“성훈 이거 수학공식 틀렷다는게 뻘하게웃김 네티즌들 진짜지독하다”
— 툐끼 (@kkkukkkuu) February 11, 2026

“Yall brutal lmaoo but yeah matrix multiplication isn’t commutative so the last part is incorrect”
— 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”
— .MR (@JooonieIndigo7) February 11, 2026

“이게틀린건가”
— 진수성찬 (@injeong49505767) February 11, 2026

“퀀트 트레이더 맞나? 대학교 3학년때 나도 배운건데 이걸 틀리나??”
— 일평 (@ilpyung98) February 11, 2026

Some questioned if he’s really a quant trader after all.

It’s unclear if the math was Sung Hun’s own work or just show production design. But he did write on the board himself in the scene.

The internet wasn’t letting anything slide — even formulas got dissected.

Screenshot of Sung Hun’s math formula

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

— 툐끼 (@kkkukkkuu) February 11, 2026

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