99 Brand, maker of shooters, spirits and hard seltzers, is looking for a fan born on September 9, 1999 to celebrate their 21st again this year—even though they’ll be turning 24.
Despite birthdays being possible any day of the year, there are more common days to have a birthday, and September 9 is the most common birth date.
“In celebration of that milestone date, and specifically to honor those with an additional ’99’ at the end of their date of birth, 99 Brand is declaring 24 the new 21,” they told Newsweek.
The birthday paradox says that in a random group of 23 people, there is around a 50 percent chance that two people will have the same birthday. It’s called a paradox thanks to the strange fact that when a room of 22 other people, a person is only comparing their birthday 22 times.
But when all 23 birthdays are compared against each other, there are more than 22 comparisons. The first person makes 22 comparisons, but the second person was already compared to the first person, so there are only 21 comparisons to make. The third person then has 20 comparisons, and so on.
Adding all of these possible comparisons together makes the sum of 253—leaving the group of 23 people with 253 chances for matching birthdays.
There are also dates that are statistically more likely to be birthdays, and birth data from the Centers for Disease Control and Prevention (CDC) report that the most popular birthday is September 9, followed by September 12 and 19.
In fact, the entire top 10 list of common birthdays is made up of September dates. Why? Many predict that this is all about the holidays.
Since pregnancy is an average of 40 weeks long, counting back from September would mean a conception date around Christmas and New Years. A 2001 study even found that December produced a peak of conceptions, with 9.1 percent in that month alone.
Babies born in 1999 are also most likely to have missed out on a big 21st celebration thanks to 2020 COVID-19 lockdowns, and 99 Brand wants to see as many cliché bashes as possible.