How do I find the middle pages of a book with the first page no. 1 and the last page no. 356 ???

356/2=178

Middle pages=178-179

well say it had 5 pages,  1,2,3,4,5   You can see that the middle page is 3

Say it has got 6 pages   1,2,3,4,5,6    Then it has got 2 middle pages  3 ans 4

So the middle page will be the (total number of pages+1)/2

So you tell me Tangrachel what is the middle page/s?

Yes that is correct - although I would have stuck to (356+1)/2 = 178.5

Middle two pages are 178 and 179