Algorithms – Pagination of a long coordinate set

Not sure if this is one of them, but I think this community will be able to give me a great answer, so I'll ask. I'm trying to solve this problem for a project I'm working on and I'm not sure what the best approach is or if this problem is trivial.

I have a long list of "coordinates" that cover each pair [1, 1] to [5000, 5000]The list looks like this [1, 1], [1, 2], [1, 3], ... [1, 5000], [2, 1], [2, 2], ... [5000, 4999], [5000, 5000],

I would like this long list to be paginated (say on pages with 100 entries). Suppose I want to go, see page 45. Which equation is best suited to find the starting index and load the 100 coordinate pairs on page 45?

Many Thanks!