There are many ways to get root or radical symbol in Ms Word. Of all these methods, if you know Math AutoCorrect method of Ms Word then you need not remember the rest.
Equation Editor Shortcut: Math AutoCorrect
Math AutoCorrect method is easy to remember and one of the efficient if not the most efficient of all. It is also similar to LaTeX method of typing root or radical sign. Unlike Alt method, you can write text/numbers inside root or radical sign too.
One thing to remember is that this method works only inside equation editor of Ms Word. You can get equation editor by navigating to Insert Menu and clicking on Equation or by using a keyboard shortcut i.e. Alt + =
List of Equation editor shortcut for typing square root, cube root, 4th root & nth root and text inside root sign. In the following shortcut <sp> stands for space bar. Only after space bar, Ms Word triggers conversion of Math Autocorrect.
Ms Word shortcuts for square root and cube root are \sqrt() and \cbrt() respectively. Text required inside these symbols are placed inside the parenthesis. These shortcut works work best inside equation editor .