Unlucky for some? Friday the 13th – also known as Black Friday – has long been considered an unlucky day.
That’s where the fear came from… and what is it all about?
Should we all be on our guard?
As part of Science Foundation Ireland Science Week, Dr Richard J., of the UCD School of Mathematics and Statistics. Smith has compiled a list of thirteen exciting facts about the number thirteen:
Paraskevidekatriaphobia is the fear of Friday the 13th.
2. Calendar Talks
According to the Gregorian calendar, the 13th day of the month is more likely to be a Friday than any other day. In 2015 three events occurred on 13 Fridays: February, March and November. Next time it will happen in 2026.
3. Unlucky for some
Bad things have happened on this day – on Friday, 13 October 1307, the French King Philip IV ordered the arrest, torture, and subsequent execution of hundreds of Knights Templar military orders. Many modern writers, such as Dan Brown in his novel The Da Vinci Code, have succumbed to the superstition incorrectly associated with this terrifying story!
4. Horse Tips
Ties permitting, there are exactly 13 possible ways in which the three fastest horses could end up in horse racing.
5. Horrifying statistics
The number 13 is regarded in many cultures as a somewhat sinister number, the bearer of the ominous sign, when its much-lauded neighbor 12 (of the months of the year, the sign of the zodiac, the son of Jacob, the apostles of Jesus). And compared to the days of Christmas fame, to name a few).
6. Number Facts
13 is a prime number, that is, a number greater than one that can only be divided by itself and one. For example, six is not a prime number, because it can be divided by two and three, as well as by six and one. In fact, 13 belong to the more prestigious club of so-called Wilson primes, of which only three are known. If there is a fourth, it must be over 20 million million.
Prime numbers have fascinated mathematicians for millennia because they are the building blocks of all numbers, and nowadays they are used globally every second of every day – whenever a credit card transaction is made online, those numbers are generated by a computer. Prime numbers are used to preserve the details. Critical eyes.
7. Creepy Creep
Many species of cicada moth in the Americas have a life cycle of 13 or 17 years (another major one). Some believe that these primordial life cycles help them avoid predators that appear in their habitat at regular intervals.
8. Introduction to Fibonacci
13 is also a member of the famous Fibonacci sequence, introduced in the 13th century. This sequence starts with zero and one, and the next number in the sequence is always the sum of the two preceding it, so we have 0+1=1,1+1=2, 1+2=3, 2+3= 5 , 3+5=8 etc. If you want to know why rabbits breed so quickly, look no further than the Fibonacci sequence.
Fibonacci is also responsible for introducing the decimal number system to Europe. Developed centuries ago by Indian mathematicians, and adopted by the Arabs, it revolutionized European banking and business because arithmetic with decimals is much easier than with clunky Roman numerals.
9. Lucky for some!
In some countries, such as Belgium, some employees receive a “13th Month” pay check, so the number 13 may actually be quite a lucky number.
10. Horror Flix
12 films have arrived on Friday, the 13th horror franchise. A 13th was supposed to release in 2017, but it was never made on screen…
Alas, the origins of the Friday the 13th superstition seem to be far more mundane – it appears to be no more than a hundred years old, and may be a combination of two things traditionally associated with bad luck, namely Friday and the number 13.
12. Hotel Trivia
The fear of the number 13 means that hotels and hospitals often leave the 13th floor, and airports sometimes leave Gate 13 silent.
Triskaidekaphobia is the fear of the number 13.