, 2012

On the first day, Jakob read $210$ pages of the book. Suppose that on the second day he read $n$ pages. Then the sum of the numbers on these pages was equal to $211 + 212 + 213 + \ldots + (210 + n) = 210n + \frac{n(n+1)}{2}$, hence $210n + \frac{n(n+1)}{2} = 4410$. From this we get $210n \leq 4410$ or $n \leq 20$. Taking $n = 20$ gives us $210n + \frac{n(n+1)}{2} = 4410$, from which we conclude that on the second day he read $20$ pages, and he still needs to read $630 - 210 - 20 = 400$ pages to come to the end of the book.