When asked about South Korea's much higher per capita Coronavirus testing results he made the following statement:
“I know South Korea better than anybody. It’s a very tight (sic). Do you know how many people are in Seoul? Do you know how big the city of Seoul is? 38 million people. Bigger than anything we have. 38 million people all tightly wound together.”
Since the question is based on per capita testing the size of the population isn't really relevant but that is just the beginning of his display of idiocy.
Seoul is not 38 million it is between 9-10 million.
Where did he get 38 million? If you go to the wiki page you will see that Seoul is 38 meters above sea level
Elevation 38 m (125 ft)
Population (2020[2])
As first mentioned on Morning Joe Trump was probably handed a copy of the wiki page and committed to memory the elevation as the population.
However the man who knows more about Seoul than anybody had no idea where it was located just a few months ago
https://www.vox.com/world/2019/12/5/20996986/trump-seoul-north-korea-move-bergen-book
After seeing a satellite image showing that Seoul — South Korea’s capital, home to 10 million inhabitants — sits just 15 miles south of the country’s heavily militarized border with the North,Trump asked, “Why is Seoul so close to the North Korean border?”
He then made a rather unorthodox suggestion: “They have to move,” Trump said, referring to the city’s residents. “They have to move!” he repeated. Those in attendance at the Oval Office briefing were uncertain whether or not Trump was joking, Bergen writes.
Trump, Bergen notes, had already been briefed numerous times on the danger Seoul faces every day. The city is in direct firing range of thousands of pieces of North Korean artillery that are already lined up along the border between the two countries, also known as the demilitarized zone (DMZ). Around 70 percent of North Korea’s ground forces are within 90 miles of the DMZ, presumably ready to move south at a moment’s notice.
This is why we don't have sharp objects in the house anymore.