Facebook will tell Congress this week that its current "best estimate is that approximately 126 million people may have been served" at least one story posted by the Kremlin-linked troll farm the Internet Research Agency (IRA) between June 2015 and August 2017, according to copies of the prepared testimony of Facebook General Counsel Colin Stretch obtained by CNNMoney and Axios. Facebook has 213 million monthly active users in the U.S., so that would suggest Russian ads hit more than half of U.S. Facebook users during the 2016 election.

Facebook says those posts were "a tiny fraction of the overall content on Facebook," but as CNN's Dylan Byers points out, it's also a big uptick from Facebook's earlier estimates.

Stretch says the IRA served content directly to 29 million users, but those users shared it, broadening its reach to 126 million. Similarly, an estimated 11.4 million people saw ads purchased by the IRA. Stretch says the Russian ads are "deeply disturbing," and "seemingly intended to amplify societal divisions and pit groups of people against each other." Facebook says it does not know how many of the 126 million people actually saw the Russian content they were served.

Twitter and Google will also testify that the Russian trolls used social media to reach more of the electorate than previously acknowledged. Google will say that it has evidence that Russian operatives uploaded at least 1,108 videos to YouTube with 43 hours of content, and paid at least $4,700 for search and display ads, The Washington Post reports. Twitter will acknowledge that 2,752 accounts controlled by Russian operatives, not just the IRA, and 36,000 Russian bots tweeted 1.4 million election-related tweets, reaching 288 million Twitter users. Peter Weber

At 94 years and 172 days old, Jimmy Carter is now the longest-living U.S. president.

Carter, the 39th president, was born on Oct. 1, 1924. When George H.W. Bush died in November, he was 94 years and 171 days old. Carter was also the first American president born in a hospital.

In office for one term, he has spent the last several decades dedicated to service, building houses with Habitat for Humanity and launching the nonpartisan and nonprofit Carter Center, which focuses on public policy. In 2002, he received the Nobel Prize. Carter announced in 2015 that he had cancer, which started in his liver and spread; he underwent surgery, and is now cancer-free. Deanna Congileo, a spokeswoman for the Carter Center, told NBC News the organization is "grateful" for Carter's "long life of service that has benefited millions of the world's poorest people." Catherine Garcia

National Oceanic and Atmospheric Administration scientists on Thursday said "conditions are primed" for flooding in the Plains and Midwest that "could be worse than anything we have seen in recent years."

Mary Erikson, deputy director of NOAA's National Weather Service, said the "stage is set for record flooding now through May," because river levels are already high, soil moisture is above-normal, and there is substantial snowpack in the northern Plains, The Washington Post reports.

This week, there was deadly flooding in Nebraska and Missouri, and that could be just "a preview" of what might happen this spring. "This is potentially an unprecedented flood season," Edward Clark, director of NOAA's National Weather Center, said. "It may become more dire in the coming weeks." The NOAA's spring flood outlook has 200 million Americans at risk, primarily those living near the upper, middle, and lower Mississippi River basins; the Great Lakes; and the eastern Missouri River, lower Ohio, lower Cumberland, and Tennessee River basins. Catherine Garcia

In one year, Tanitoluwa Adewumi went from not knowing anything about chess to becoming New York's newest champion.

Adewumi, 8, started learning the game last year at his school, P.S. 116 in New York City. Adewumi and his family came to the U.S. from Nigeria two years ago, seeking religious asylum; they are Christians, and fled to escape the terror group Boko Haram. Adewumi's coach, Shawn Martinez, said the third-grader loves to play, and is always practicing. "He smiled every time he did anything on the board or learned something new," he told NBC New York. "I could just tell this game was for him."

Over the weekend, Adewumi kept his undefeated streak alive, winning his age group in the New York State Primary Chess Tournament. Adewumi will soon have a place to display his huge trophy: the family has been living in a homeless shelter, but a GoFundMe started for them this week has raised more than $160,000, and they will soon move into their own home. Adewumi is gearing up for the national championship in May, and is inching closer to his goal. "I want to be the youngest grandmaster in the world," he said. Catherine Garcia

While he believes President Trump is "morally unfit" to be the country's leader, former FBI Director James Comey isn't wishing that Special Counsel Robert Mueller reveals in his final report that Trump is "a criminal."

In an op-ed published Thursday night in The New York Times, Comey declares that he's just happy Trump hasn't shut down Mueller's investigation, and if it stays that way, "justice will have prevailed and core American values will have been protected at a time when so much of our national leadership has abandoned its commitment to truth and the rule of law."

Comey, who was fired by Trump in 2017, asserts that he doesn't care at all whether Mueller concludes that Trump "knowingly conspired with the Russians in connection with the 2016 election or that he obstructed justice with the required corrupt intent." He does have one hope, though: that Trump is not impeached and removed from office before his term is over.

"I don't mean that Congress shouldn't move ahead with the process of impeachment governed by our Constitution, if Congress thinks the provable facts are there," he said. His concern is that if Trump is removed from office, "a significant portion of this country would see this as a coup, and it would drive those people farther from the common center of American life, more deeply fracturing our country." Read the entire op-ed at The New York Times. Catherine Garcia

Marine Corps Gen. Robert Neller wrote in two internal memos that President Trump's "unplanned/unbudgeted" deployment of troops to the southern border has posed "unacceptable risk to Marine Corps combat readiness and solvency," the Los Angeles Times reports.

The memos obtained by the Times are dated Feb. 19 and March 18, and sent to Acting Defense Secretary Patrick Shanahan and Navy Secretary Richard Spencer. Neller wrote that because funds have been shifted to border security and recovery costs from Hurricanes Michael and Florence are high, he has had to postpone much-needed base repairs, and cancel or scale back military training in Indonesia, Scotland, Mongolia, Australia, and South Korea.

Neller added that Marines "rely on the hard, realistic training" of the exercises to "develop the individual and collective skills necessary to prepare for high-end combat." These memos, Sen. Richard Durbin (D-Ill.) said, show that the Pentagon should not be diverting funding due to the whims of Trump. "If the president won't listen to the American people or Congress, then listen to the commandant of the Marine Corps," he said in a statement. Catherine Garcia

European Union leaders on Thursday offered the United Kingdom additional time to leave the bloc, delaying Brexit until May 22 if British lawmakers agree to Prime Minister Theresa May's withdrawal deal.

If not, the EU will accept a delay until April 12. The UK was set to leave the bloc on March 29.

Britain's Parliament has twice shot down May's EU deal, with lawmakers split on how to leave the EU, and if they should do so at all. "I will make every effort to make sure we can leave with a deal and move our country forward," May said. Catherine Garcia