Have you looked at your ID card carefully?
Most ID numbers are made up of numbers, but some of them have "mysterious identities" – the last digit of their ID cards is X!
Why is it an "X"? Should this "X" be pronounced "fork" or "Ax"? Why do many technology products and film and television dramas like to use X?
The Roman letter X on the ID card
The rules for arranging ID numbers are exquisite, and the last digit is the "check code", which is calculated from the formula and represented by 0 to 10.
The problem is that the number of digits in the ID card is fixed, and the last digit verification code cannot be a two-digit 10! To solve this problem, we replace the Arabic numeral 10 with X, which is the 10 in the Roman numerals.
Therefore, the X on the ID card should be read as shí.
Before Arabic numerals were introduced to Europe, Europeans used Roman numerals to count, and the rules were as follows:
I=1;X=10;C=100;M=1000
V=5;L=50;D=500
Smaller numbers on the right, let them add up, such as VIII.=8, XII.=12;
Smaller numbers are on the left, so subtract them, such as IV.=4, IX.=9;
In addition to appearing on clocks, Roman numerals are also used to indicate the year of television program production, such as MMXXI, MMXX, MMXIX, MMXVIII, MMXVII, MMXVI, corresponding to 2021, 2020, 2019, 2018, 2017, and 2016, respectively.
Mysterious X
In the field of technology, X symbolizes "experimentation", "exploration" and "innovation", becoming an abbreviation for experimental.
For example, Space X, which carries Musk's dream of Mars colonization, is fully called Space Exploration Technologies (Us Space Exploration Technology Company), and X stands for Exploration.
Google's department dedicated to technology research and development is called Google X, which uses X to represent its innovative spirit.
However, the X in the Apple phone iPhone X is to commemorate the tenth anniversary of the release of the Apple phone, and the X is the Roman numeral 10.
There is another common use of X - XL.
This is an abbreviation for extra large and stands for "king size".
Source: Qilu Safety Learning