1. Stefan's bookmark fell out of his book, and he was unable to remember what page he had got to. He did, however, remember that he had passed page 800 already, and the total of all numbers below the pages the bookmark was between, was exactly the same as the total of the numbers above them. Given that the book was 1273 pages long, what were the page numbers of his 'place'?

Pages 900 and 901

Pages 860 and 861

Pages 880 and 881