Texas was the 28th state admitted to the U.S.
28 is the 4th prime times the second prime squared, which happens to be 4.
It’s also a perfect number, as others have said: 1+2+4+7+14=28, and for whatever reason 1 is counted, but not 28. (Well, if the number itself were counted, there would be no perfect numbers.)
Need sleep so much…
The First World War was triggered by the assassination of Archduke Franz Ferdinand on June 28, 1914
It was formally ended by the Treaty of Versailles which was signed on June 28 1919.
The Three Mile Island incident took place on March 28 1979.
The most common isotope of Silicon has an atomic weight of 28
Title 28 of the U.S. Code deals with the judiciary and judicial procedure.
“28 Days” is a nasty Sandra Bullock movie…
The Space Shuttle Challenger expired on January 28, 1986.
28 years ago was the bicentennial.
Oh… so “Pefect Numbers” are a real math thing? Not just made up here? What the hell is the purpose of that? Who cares? Why? Who came up with that? Are they as significant as prime numbers? Would the aliens be just as likely to send us an encrypted message in a pattern of Perfect Numbers as they would Prime Numbers? You know… like they did in that one movie…
The tweny-eighth result of an Altavista search of “twenty-eight” is a page entitled “Twenty-Eight Common Mistakes,” which contains a list of 29 common mistakes in job hunting.
Erk. Twenty-eighth. The 29 isn’t a typo, though.
Woodrow Wilson was president number 28.
A sci-fi movie from 1957 was titled “The 27th Day”.
If Hollywood ever films the “long-awaited” sequel, would they call it “The 28th day” ?
Well, I’d say we have more than enough “fun facts”.
Thanks for all your help folks.
Of course, if you feel you must post more “fun facts” about 28 please feel free to do so.
The Pythagoreans, who were intrigued by numbers and attributed mystical significance to (at least some of) them, designated the ones that are sums of their divisors as “perfect numbers.” For many centuries afterward, scholars were then also more concerned with the mystical or religious significance of these numbers than their mathematical properties. Philo Judaeus of Alexandria, and later St. Augustine, suggested the perfection of God’s handiwork because the world was created in 6 days, which is the first perfect number; as well, other Biblical commentators have used 28 – the number of days in a lunar cycle* – as evidence of the perfection of the Universe.
Mathematically, perfect numbers are intimately associated with Mersenne primes, where the search for new values has, AFAIK, no practical applications (other than discovering new algorithms for finding more Mersennes), but then you get into the larger question of how or why pure mathematics is useful at all.
Since we’re done with “28 fun facts,” it is perhaps now appropriate for me to point out that my number theory textbook only lists 27 perfect numbers – which were the only ones known at the time of publication. The 28th, and many more, have been discovered since then. That’ll tell you how ancient I am.
- For some reason, I thought it was 29.5 days. But what do I know.
Earthling
The Moon’s sidereal period is about 28 days whereas its synodic period is 29.5 days so you are partially right.
The sidereal period is the time it takes the Moon to reach the same position in the sky (the background of the stars) or the time it takes the Moon to return to the same celestial longitude.
The synodic period which is much more widely known is the time for the Moon to go through 1 complete phase cycle. For example, the time from one Full Moon to the next averages 29.5 days.
A license plate on the cover to the Beatles album “Abbey Road” reads “IF28”, which spun the theories that Paul McCartney would die at that age. 
28 is the basis of one of Abbot and Costello’s best comedy sketches: 7 X 14 = 28
They “prove” that the equation is correct. Three different ways. 
Sorry – I made a typo. The equation is 7 x 13 = 28.
Saying 7 x 14 =28 is ridiculous.
There are 28 digits (width of finger) in a cubit.
“28” was the name I gave to my pet budgie when I was little.
Seriously.
I used to claim I was 28 until I was 37… and get away with it…
I’m 32 now… honest…