Top White House economist says Trump's GDP and unemployment claim was wrong

White House economist Kevin Hassett on Monday fact-checked a seemingly extraordinary claim about the country's GDP growth rate overtaking the unemployment rate for the first time in 100 years.

The only catch ... the claim was made by his boss, President Trump.

"So I can tell you what is true," Hassett, the chairman of the Council of Economic Advisers said from the podium of the White House briefing room in response to a question about Trump's tweet from Monday morning. "What is true is that it's the highest in 10 years. And at some point, somebody probably conveyed it to him, adding a zero to that, and they shouldn't have done that."

“I'm not the chairman of the Council of Twitter Advisers," Hassett said about the tweet.

Earlier in the day, Trump made the claim on Twitter that "The GDP Rate (4.2%) is higher than the Unemployment Rate (3.9%) for the first time in over 100 years!"

The Gross Domestic Product rate and the unemployment rate both measure important -– but separate and unique-- rates of change for the economy. The GDP is the rate of the entire economic output for the United States and it’s used to measure, on a quarterly basis, the overall health of the economy. The GDP rate Trump's tweet refers to is for the second quarter of 2018 -- and while that rate might continue the for the rest of the year it's not a sure thing by any means.

The unemployment rate, meanwhile, which comes out each month, is the percentage of unemployed people out of the entire labor force. While the two rates are related in the sense they're indicators of how well the economy is doing, it’s like comparing apples and oranges.

Still, the last time the GDP was higher than the unemployment rate was in 2006, when President Bush was in the Oval Office, and since the government began tracking economic numbers in the 1940s, the GDP has been higher than the unemployment rate dozens of times, according to economic data tools from the Federal Reserve Bank of St. Louis.

Hassett denied that his presence at Monday's White House press briefing, the first in 19 days, was because former President Obama claimed on Friday that the Trump administration inherited an economic recovery spurred by his presidency. Standing at the podium with charts marked in blue, for the time when Obama was in office, and red, when Trump came to office, Hassett touted economic growth under the Trump administration.

His briefing, Hassett said, was not in reaction to Obama and had been in the works for weeks.

“We were prepared to do this briefing a few weeks ago, and there's not in any way a timing that's related to President Obama's Friday remarks,” Hassett said.

And with regard to Obama's claim?

"I can promise you that economic historians will look back and say there was an inflection point when President Trump was elected," Hassett said.

On Friday, Obama said that the recovery started when he was in office.

“When you hear how great the economy’s doing right now, let’s just remember when this recovery started,” Obama said. “When you hear about this economic miracle that’s been going on, when the job numbers come out, monthly job numbers, suddenly Republicans are saying it’s a miracle. I have to kind of remind them, actually, those job numbers are the same as they were in 2015 and 2016.”

In another Trump tweet Monday, he appeared to mischaracterize a comment Obama made more than two years ago, writing: “President Trump would need a magic wand to get to 4% GDP,” stated President Obama. I guess I have a magic wand ..."

“President Trump would need a magic wand to get to 4% GDP,” stated President Obama. I guess I have a magic wand, 4.2%, and we will do MUCH better than this! We have just begun. — Donald J. Trump (@realDonaldTrump) September 10, 2018

Obama used the words "magic wand" on the campaign trail in June 2016 while criticizing Trump's claims that he would boost American manufacturing jobs by getting American companies to produce more goods in the U.S.

“He just says, 'Well, I’m going to negotiate a better deal.' Well, what, how exactly are you going to negotiate that? What magic wand do you have? And, usually, the answer is he doesn’t have an answer,” Obama said then.

Obama did not mention the GDP.

ABC News' Alexander Mallin contributed to this report.