1. Stop the cursor at the position where you want to insert the square symbol, and open the sogou input method.

2. Click the right mouse button on the column box of the input method, select "Symbol Expression" in the list menu, and continue to select "Symbol Daquan".

3. After the "Symbol Dictionary" dialog box pops up, select the "Math/Unit" option and find the square symbol in the list. , click the mouse to insert the specified location.