Donald Trump is very adamant that he should be president in part because he is not financially beholden to anyone. "I’m using my own money," he said during his campaign announcement speech. "I’m not using the lobbyists. I’m not using donors. I don’t care. I’m really rich." To prove his point, he held up a sheet of paper detailing his assets. Billions in real estate and stocks! Rich guy. Doesn't need donors.

It didn't take long, though, for people to point out the obvious. Entrepreneur Mark Cuban -- himself so rich that he has his own social network -- pointed out that there's a big difference between being worth billions of dollars because you own office buildings and being able to spend billions on a campaign. "Let’s say you own a painting that gets appraised at $10 billion," Cuban said on "Cyber Dust" (his social network). "That gives you a net worth of 10 billion. But that does not mean you have a lot of cash. How much cash does Donald have? We don’t know for sure."

Even after Trump provided details of his finances to the Federal Election Commission, we still don't know for sure. Bloomberg tallied up his assets and figured he had $70,000,000 on-hand. An expert contacted by Politico put the number higher, at $250,000,000 -- once he liquidizes some securities.

So how much of a campaign does that get you? To answer that question, we need to answer a bunch of other questions.

- How much money is Trump spending on his campaign?
- Despite not (really) soliciting donations, how much is he getting?
- Does he have additional income?

We know how much Trump has spent so far. In the second quarter of 2015, he was a candidate for 15 days and spent $1.5 million. That's $100,000 a day.

He also took in about $96,000 in donations. That's about $6,400 a day -- meaning that Trump was spending just under $94,000 a day on net.

So if Trump 1) keeps spending the same amount and 2) doesn't get any additional money, he has enough to campaign for 748 days, if Bloomberg's estimate is right. That brings him out to July 2017. And if Politico's higher figure is accurate? That's enough for 2,671 days of campaigning -- extending past his reelection and into 2022.

Your first instinct is probably to say: Well, he has to spend more than that at some point. To which we would reply: Does he, though? The answer is yes, probably, but we wouldn't be surprised if he figured that showing up once a day to holler in the direction of some TV cameras could get the job done.

So let's assume that he does need to start ramping up his spending. That he decides, heck, maybe we'll print some mail and run some TV ads. (Oh man -- imagine those ads! Imagine Donald Trump's TV ads. What will they be? Helicopters landing on skyscrapers with beautiful blondes stepping out, waving American flags? A tour of Trump's Manhattan penthouse as Trump explains in a voice-over that he's happy to downgrade his digs? Construction-worker-actors wiping their brows as they explain that Trump is their man for the job? This will be so good, guys.)

How much is it going to cost him? We can look at a recent expensive primary election as a guide: The Democrats' in 2008.

In the third quarter of 2007, Barack Obama spent about $21.5 million -- $24.8 million in 2015 dollars. By January, he was up to $30.5 million (or $33.8 now). In February, as he was locking the nomination down, he spent $42.9 million -- or, in 2015 dollars, $1.63 million dollars a day.

If we assume that a fleshed-out Trump campaign is spending similar amounts per month, and using only his own money, Trump has enough to get him to the end of the year in the Bloomberg scenario, and almost to June in Politico's.

That's using 2008 figures. If the campaign were twice as expensive as 2008 -- not impossible, given that super PACs will be competing for airtime and resources in a way they weren't then -- Trump only has enough money to get him to late October or to mid-February. That's cutting it close.

We've been ignoring our third question above: How much Trump has in additional income. In the press release that accompanied his FEC filing, Trump reported a 2014 income of $362 million. Much of that was in the sale of stock; more was from licensing deals. He's lost some money this year, but let's just assume for the sake of argument that he's making $365 million in 2015. That's a million dollars a day.

And that changes things.

With that income, assuming costs near Obama's 2008 spending (adjusted into 2015 dollars), Trump has enough money to make it to next September -- or, under Politico's scenario, all the way to Election Day. Granted, he'd be very cash poor, and other things might suffer, but it's possible.

We're ignoring a lot of variables: Discrepancies between party and candidate spending, the growth of outside groups, yada yada yada. That aside, though, it seems as though Trump might -- might -- be able to stretch his cash out through next November, should political fortunes smile on him. But if he gets the Republican nomination, don't be surprised to see a "for sale" sign outside of one of the classiest office buildings in New York City.

He doesn't care. He's really rich.