[JSWolf]

Originally Posted by RbnJrg

All the answers I saw. were good solutions; I add just one more for the records.

Add this in the place you wish in your .xhtml file (it can be any place, even inside a paragraph or title, no matter):

<span class="pgnum">XX</span>

where XX is a number, of course, and in your .css stylesheet add the following:

.pgnum {
    display: none;
}

That's all

Not a good idea as not all ePub reading software will respect display: none.