U.S. Republican presidential candidate, real estate mogul and TV personality Donald Trump acknowledges supporters while formally announcing his campaign for the 2016 Republican presidential nomination during an event at Trump Tower in New York June 16, 2015. Reuters

Real estate mogul Donald Trump announced his presidential campaign -- and declared his net worth -- in a winding, off-book speech at the eponymous Trump Tower in New York City Tuesday. According to the statement released by Trump, he's worth about $8.74 billion. But his net worth has been a point of contention for years.

In his speech Tuesday, Trump said he would spend his own money in the campaign and that his experience building his personal fortune would translate into job creation as president. He has already dubbed himself as the "most successful person ever to run for the presidency, by far." In his speech Tuesday, he said bluntly, "I’m really rich.”

Trump's main business is real estate and he listed 40 Wall Street -- or the Trump Building -- in New York City, and the Bank of America building in San Francisco as two of his marquee properties. His website lists many properties, including a range of golf courses, resorts and hotels. He's also a popular TV personality on the television show "Celebrity Apprentice."

The documents released by Trump peg his net worth at about $8.74 billion. The number comes from subtracting liabilities of about $502 million from his reported total assets over $9.2 billion. The Washington Post reported Tuesday morning that longtime Trump advisers put the financials together. The paper consulted experts who said his real worth could be different, depending on who is crunching the numbers.

Forbes has estimated Trump's worth at about $4.1 billion -- less than half what he claims. If Tuesday's estimate of about $9.2 in assets is correct, that would mean Forbes perhaps estimates Trump's liabilities to be about $5.1 billion. The magazine pegs him at No. 133 on the list of richest people in the United States. The magazine's webpage about him says his brand exposure has been boosted by his "Celebrity Apprentice" appearances, along with speaking engagements and his ownership of the Miss Universe and Miss USA pageants.

The Washington Post report suggests Trump could boost his asset figure but remain financially illiquid since much of his wealth is "tied up in hotels, housing and office buildings." There can also be differences in determining the actual value of assets -- like buildings, housing and hotels. The paper did not report on the $8.74 billion net worth figure Trump talked about Tuesday, but rather just the assets total.

Trump's net worth was the subject of much discussion in 2005, when author Timothy O'Brien questioned Trump's wealth in his book "TrumpNation: The Art of Being the Donald." In an excerpt from the book published in the New York Times, O'Brien said sources connected with the mogul estimated his worth between a mere $150 million and $250 million. Trump said he told O'Brien his worth was between $4 billion and $6 billion. Trump eventually unsuccessfully sued the author, saying his reputation had been damaged.

Trump said Tuesday he was eager to disclose his net worth -- something that would not have been necessary if he decided not to run. "I’m proud of my net worth," he said.