Are you looking for √ (Checkmark) alt code?
You have to use a keyboard that has a numeric keypad usually, all desktop keyboards had a numeric keypad. Today’s laptop is very rare having a numeric keypad, to overcome this you can use USB external keyboard or onscreen keyboard.
To insert a checkmark in Excell, Windord, or Powerpoint (Microsoft Office Family). Insert Object and choose Wingdings font. Wingdings is in the default list font of Windows so you will find it without the need to add the font.
You will find checkmark symbol at the end of symbol list along with other useful symbols like an arrow, windows logo, cross-check and more.