Go to Insert > Equation . You can type \sqrt followed by a space, and Word will automatically convert it into a radical symbol with a box for your number.
This reveals a deep truth: The plain-text square root (√) is a compromise. It is a logogram. It says "square root of the next thing," but relies on parentheses ( √(x+1) ). The typeset radical, by contrast, shows you the scope. The Mac, through apps like Typora, Overleaf, or the native Notes app (via Cmd + Shift + E ), is one of the best LaTeX machines ever built. square root on mac