X stands for 10 in Roman numerals, and is usually used to represent unknowns in algebra and mathematics. When algebra was introduced into Europe from Arabia, the word shei, which means "unknown" in Arabic, was translated into xei, so the initials X became the common code name of unknown.

Whether it is uppercase or lowercase, X is the appearance of two wooden sticks crossing each other, so the basic meaning of X is "crossing and mixing together". Exit is the intersection of inside and outside, axis is the thing that connects the two parts, and mix is a mixture of many things, so they all contain the letter X.

The correct way to write the letter x

The correct way to write a capital x: the first stroke is inclined to the right, and the second stroke is inclined to the left, occupying the top two cells of four lines and three cells.

The correct way to write lowercase x: the first one bends left, and the second one bends right, occupying the middle cell of four rows and three squares.

The 24th letter of the English alphabet. Pronunciation /eks/, because of its pronunciation, is the letter with the least initials in English letters. X was originally a pictographic symbol for kissing. If it's written as an X, it's a bit like kissing with two mouths.