Trump Tower on Fifth Avenue in Manhattan, New York. Reuters / Eduardo Munoz Donald Trump lives in a penthouse that he says is on the 66th to 68th floors of his eponymous building. There's only one problem with that: According to New York City documents, Trump Tower has only 58 floors.

It turns out the real-estate-mogul-turned-presidential-candidate frequently misstates the floor counts of his buildings to exaggerate their height without changing the actual numbers.

Taking Trump Tower as an example, an atrium takes up the first 300 feet of the building's height, according to an interview Trump did with The New York Times in 2003, which was quoted by The Associated Press.

Because of that, Trump was able to estimate — by taking into account the average height of a ceiling on a floor in New York City — that it took up about 30 stories. He was thus able to name the first real floor the 30th — 10 more than it should have been, according to the AP. The building is 664 feet tall.

Many buildings use this principle, to an extent. There's no legal requirement to tie the building floor numbers to the actual floors the buildings have, except in official documents. Many hotels skip the 13th floor in their counts for superstitious reasons, and other buildings with large atriums must use a mathematical formula to estimate how many floors they take up.

Unfortunately, Trump fudged the numbers a bit, as his formula didn't take into account the fact that Trump Tower's luxury residences and commercial space had ceiling heights that are much higher than the average. The crude formula does not include the space left between floors for utilities. As Bloomberg noted, the developer skipped the sixth through 13th floors.

The public atrium in Trump Tower lobby. Kate Taylor

It's not uncommon for a building to have a different floor count than is stated in the elevators, especially in New York City, where a building with more floors could be seen as a more desirable place to live.

"Developers have a tendency to exaggerate the floor count," Ben Mandel of the Council on Tall Buildings and Urban Habitats told the AP.

Most developers don't blatantly exaggerate the number of floors so dramatically, however. Trump required some buyers in other Trump buildings to sign a document acknowledging that their apartment unit was not really on the floor stated, according to the AP's report of the Times story.

Even more egregious than Trump Tower? Trump World Tower, at 845 United Nations Plaza. Supposedly, it has 90 floors. But if you stand on that top floor, you may be disappointed to learn you're only 72 stories above the ground.