Learn English – the basic unit of a chain called in English

Are you talking about a single piece of paper, that's not attached to a book? If so, don't use either "page" or "blank page", because a page is a sheet of paper bound inside a book. Technically, a page of paper is only one side of a sheet. If you wanted to talk about the sides of a single loose piece of paper, you'd just say the "side of the paper". Thus "page" is not used in the context of single pieces of paper.

You could use:

• (blank) sheet of paper
• (blank) piece of paper

And because "sheet" is so specific of a word, sometimes people drop "of paper" in "sheet of paper"

• (blank) sheet

I guess you could technically do the same with "piece of paper", but "piece" is too vague, so people don't usually drop "of paper".

P.S. Wikipedia tells me the technical term is a "leaf of paper", but nobody says that in daily use.

The term is callus: (plural calluses)

• a hard and thickened area on the skin and especially on the hands or feet

(M-W)

Usage example:

• He was a migrant handyman with no calluses.