Real Talk!

On March 13th, my little girl will be 15. I remember being 15. Fifteen is an interesting number!

As the product of two sacred numbers (3 X 5), 15 naturally has religious significance. In ancient Nineveh 15 priests served the goddess Ishtar, and the city had 15 gates.

Fifteen is a triangular number and a hexagonal number, a pentatope number, and the 4th Bell number. Fifteen is the double factorial of 5. It is a composite number; its proper divisors being 1, 3 and 5. With only two exceptions, all prime quadruplets enclose a multiple of 15, with 15 itself being enclosed by the quadruplet (11, 13, 17, 19). 15 is also the number of super singular primes.

The 3 X 3 magic square has 15 as its magic constant, and in Babylon this square was associated with Ishtar. Fifteen is the magic constant of the unique order-3 normal magic square. 15 is the smallest number that can be factorized using Shor's quantum algorithm.

There are 15 solutions to Znám's problem of length 7. 15 is a repdigit in binary (1111). In hexadecimal, as well as all higher bases, fifteen is represented as F.

Messier object M15 is a magnitude 7.5 globular cluster in the constellation Pegasus.

There were 15 steps between the Ezrat Nashim and the Courtyard of the Temple in Jerusalem, on which the Levites stood and sang during the offering of sacrifices. Fifteen Psalms (Chapters 120-134), collectively known as the "Songs of Ascent", correspond to the 15 steps on which the Levites stood.

The 15th day of any Hebrew month is not written with the letters that represent "10" and "5" (י-ה, yodh and heh), because those are the first two letters of the four-letter name of God. Instead, the date is written with the letters representing "9" and "6" (ט-ו, teth and vav).Passover begins on the 15th day of the Hebrew month of Nisan.

Sukkot begins on the 15th day of the Hebrew month of Tishrei. Tu Bishvat is a Jewish holiday occurring on the 15th of the Hebrew month of Shevat. Shushan Purim (the day on which Purim is celebrated in Jerusalem and a few other cities in Israel) occurs on the 15th day of the Hebrew month of Adar. Tu B'Av is a minor Jewish holiday occurring on the 15th day of the Hebrew month of Av.

Fifteen is the number of days in each of the 24 cycles of the Chinese calendar. The number of guns in a gun salute to Army, Air Force and Marine Corps Lieutenant Generals, and Navy and Coast Guard Vice Admirals.
Fifteen is the number of letters in the words "uncopyrightable" and "dermatoglyphics", which are the longest words there are without repeating a letter.

The number of The Devil in the major arcana of Tarot cards is 15. The number of minutes in 1/4 of an hour, 15 min past or before an o'clock is often known as 'Quarter Past' and 'Quarter To' respectively. The M15, in New York City is the busiest bus route in the United States.

The Quinceañera or Quince Años (sometimes represented XV Años, meaning "fifteen years") is, in some Spanish-speaking regions of the Americas, a young woman's celebration of her fifteenth birthday. This celebration marks the transition from the childhood to womanhood. It serves as a way to acknowledge that a young woman has reached maturity.

Some other traditions observed in the celebration include the giving and throwing of a quince doll, signifying the girl’s last doll. The doll is thrown by the young lady to the other female children in attendance much as a bouquet is thrown at a wedding.

Another tradition is that at the beginning of the party, the birthday girl wears flat shoes but after the first dance, her father helps her change into high heels to signify she has become a young lady. Long ago, the party would announce that the girl is ready to be married, but in today's culture it means that she is ready to date.

Hmmmm. I wonder if my daughter’s boyfriend knows about all of this.