Method 1: Insert a text box-insert a special symbol-mathematical symbol √-float the text box above the text and put it on the box.

Method 2: Delete the original box-insert-symbol-font, select-Wingdings 2, and find the symbol-insert with "tick in the box".

Method 3: Delete the original box-Insert special symbols-Insert mathematical symbols √-Select the inserted √-Dot format menu-Chinese layout-circled characters. First, select box style.