Donald Trump misquoted the population of the South Korean capital by 28 million during a White House coronavirus press briefing.
The US president brought up facts about Seoul when asked by a reporter about Covid-19 testing capabilities in America.
When asked by PBS News Hour journalist Yamiche Alcindor about per capita testing in the US compared with South Korea, Mr Trump began sharing facts about the country.
“I know South Korea better than anybody," he said.
"It's a very tight... Do you know how many people are in Seoul? Do you know how big the city of Seoul is?"
He then answered his question: "38 million people. That's bigger than anything we have.
"38million people, all tightly, wound together."
He then said the US had done more tests "by far" than any other country in the world.
Seoul has a population of around 10million, according to its government website.
If the greater metropolitan areas of the city are included, the figure of 25 million still comes in wide of Mr Trump's estimation of 38 million.
Lots of people took to social media to share clips of the mistake.
One Twitter user said: "'I know South Korea better than anybody'. Miscalculates Seoul's population by 400%."
Another added: "I hate Trump 38 million times."
