Usually, when we write the letter Z, there is a horizontal line in the middle. Isn't that a horizontal line? Could it be a mistake? Don't you need strokes for English and Chinese phonetic notation? What about other drugs? It's really not used in English.

There is nothing wrong with using words in mathematics to represent an unknown number or writing algebraic fractions clearly with letters. The math teacher wrote that horizontal line to distinguish it from 2, so Z was added to math. There are too many numbers in math, which means nothing. However, when writing a capital z to represent an integer field, it should be written like this.