Answer:
Ctrl + *
Step-by-step explanation:
Non-printing characters are the characters that are not displayed at the time of printing of an document or a spreadsheet. This is used for designing a content
The few are examples like non-breaking space, the pilcrow etc
The shortcut to show or hide the non-printing characters is Ctrl + * i.e Contorl + Star
So press these two keys we can see the non-printing characters