1. Download a formula editor online, which contains everything. The specific name is MathType, which can also be downloaded directly from Baidu into the formula editor.

2. The toolbar in 2.word has a special symbol "insert".

3. In the input method, in the intelligent ABC, v+6 is a Greek letter, and the rest+1, +2, +3...+9 are defined.

4. If the input method is sogou, it will be faster, or directly click on the soft keyboard and right-click to select Input.