Two split of young boy staring into camera


9 + 10 = 21: a Vine classic

This Vine classic has withstood the test of time.


Angela Andaloro


9+10 = 21 is a Vine classic that’s still making people laugh with a simple math error years later. So many people (especially the non-math inclined) can relate to the little boy who so confidently answers a question, despite being incorrect.

9+10 = 21 origin

Of course, we all know 9+10=19. One child who was put on the spot in a Vine video that went massively viral answered “21” instead.

The video, first shared in 2013, begins with a man telling the boy, “You stupid.” He says, “No, I’m not.” It’s then that the man, presumed by some viewers to be an older sibling or a dad, asks the boy was 9+10 is.

When the boy says 21, the man reiterates, “You stupid.” The video ends there, but people had many thoughts about the boy they dubbed “21 kid.” The Vine quickly went viral, with many people remixing it to include other reaction memes at the end of the video.

21 Kid Faux Runaway Controversy

As the Vine continued to go viral, there were concerns for the boy. Social media users said that the attention was taking a negative toll on the little boy. Later that year, a news article claimed that the little boy had run away, hurt by the internet, making fun of the vulnerable moment where he was already being teased.

The article, which has since been made unavailable, said that the little boy was from Baltimore and ran away from home after going viral. According to the piece, 9+10 = 21 kid had left a note referencing the video when he left home. It allegedly read, in part, “I’m tired of everyone laffing at me.”

The rumor started to spread online, leading one creator to share a video with the boy and prove he was safe.

e he was safe.

After Vine shut down, the video lived on. It was shared in 2019 on both YouTube and Instagram.

9/10/21 Day Memes

21 kid got another day in the spotlight in 2021. At the beginning of the year, a Twitter account was created using a meme of the boy. The whole account was dedicated to counting down to 9/10/21.

Tweet that reads 'Counting the days until 9/10/21.'
@TwentyOneCount / X

The account faithfully counted down as the year progressed, and people got enthusiastic about the milestone. They managed to trend on X throughout that day—reaching number one at one point—as people contributed memes marking the occasion.

21 kids imposed over the New York City skyline with '9/10/21 judgment day' written underneath.
@TwentyOneCount / X
Meme comparing two 9+10=21 fans
math diagram showing how 9+10 could equal 21
@TwentyOneCount / X
the hashtag #nineten21 trending on X amid the 9/10/21 celebration

More iconic videos:

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