It is said that this symbol originated in England. At that time, when the British teacher was correcting the students' homework, he saw that the content of the homework was accurate, so he wrote the comment on writing "Yes" in this place, which means correct meaning. Because this comment on writing has several letters, it is very troublesome to write, and later it is represented by the first letter "R". Over time, it evolved into a simpler way of writing, which is "√". Because this symbol is easy to write, it will be popular in the world in the future.

If you carefully observe the symbol "√", you may find that it is really similar to lowercase English letters.

As for ×, because √ stands for right, it is wrong to draw a diagonal line above √, and later it gradually evolved into ×.