123movies133... | 9 / 10

Even after the Vine app shut down in 2017, the meme lived on through:

: People created absurd logical loops to "prove" the kid was actually a genius and that 9 + 10 really does equal 21. 9 / 10 123movies133...

The dialogue that launched a thousand remixes went like this: "You stupid." Kid: "No I'm not." Brother: "What's 9 plus 10?" Kid: (Without a second's hesitation) " 21 ." Brother: "You stupid." Why It Became a Legend Even after the Vine app shut down in

: The audio has been mixed into songs, movie trailers, and other viral trends on platforms like TikTok and Instagram. In the clip, an older brother is recording

The story began in 2013 with a short, six-second video that captured a simple yet hilariously confident mistake. In the clip, an older brother is recording his younger brother, who would eventually be known across the internet as the "21 Kid".

: It is still frequently referenced today whenever someone makes a glaringly obvious math error.

original sound - soundeffectpack ... Stupid? No, not. What's 9 + 10? 21, you stupid. TikTok·althea420