Here is a list of some fact about birthdays you probably don't know:
1. Before the 19th century, dates of birth were not officially noted, although baptisms occasionally were. England began keeping parish records of births, deaths and marriages in 1538 but this wasn’t implemented for the entire population until the Registration Act of 1836. The first British census in 1801 didn’t record age, and it wasn’t introduced as a question until 1831 - even then it wasn’t mandatory to answer. It wasn’t until the 1851 census that people had to record their precise ages.
2. Birthday Paradox
If there are 23 people in a room there is a 50-50 chance that two of them will share a birthday. This is known as the birthday paradox, because it appears there are only 22 possible pairs and therefore a low chance of a match. In fact, because every guest could match with every other guest, there are 253 possible combinations (1+2+3+4… up to 22) and the probability of finding a successful one is 50.048%. If you are confused by that then try view it this way: [If you have a list of 23 people, comparing the birthday of the first person on the list to the others allows 22 chances for a matching birthday, the second person on the list to the others allows 21 chances for a matching birthday - in fact the 'second' person also has total 22 chances of matching birthday with the others but his/her chance of matching birthday with the 'first' person, one chance, has already been counted with the first person's 22 chances and shall not be duplicated, third person has 20 chances, and so on. Hence total chances amounts to 253]. The probability reaches 100% when the number of people reaches 367 (since there are 366 possible birthdays, including February 29). However, 99.9% probability is reached with just 70 people. These conclusions include the assumption that each day of the year (except February 29) is equally probable for a birthday. In fact you don't need bother about this if you aint a statistician.
3. Queen's Birthday
The Queen’s actual birthday is April 21 but she celebrates her official birthday on a suitable Saturday in June (the Government chooses which one). One of the reasons is to ensure good weather for the Trooping the Colour ceremony, held to mark the monarch’s birthday since 1748. The Queen has attended all the ceremonies during her reign apart from in 1955, when the parade was cancelled due to a rail strike.
4. Happy Birthday Song
The “Happy Birthday” song originated in 1893 when teacher Mildred Hall thought of the
tune. Her sister Patty added words and they christened the piece Good Morning to All. It was intended to be sung as children entered the classroom but was switched to be sung to the teacher, and became Good Morning to You. As the song grew in popularity, it was sung outside schools and became Happy Birthday to You. The song is protected under copyright until at least 2030.
5. Cards and Present
Britons send more than 300million birthday cards a year. Cards that play a song when you open them use more computing power than was used to send man to the moon. In the 19th and early 20th centuries, a popular 21st birthday present was to have all your teeth removed and replaced with a set of dentures – the idea was it would prevent the expense of dental treatment later in life. Shirley Temple received 135,000 presents for her eighth
birthday.
6. Birthday as count-up and count-down timer
Each time you celebrate +1year on earth you are as well celebrating -1year to the grave. So birthdays counts down in same manner as it counts up.
