A chunk of pages is missing from a book. The sum of the missing page numbers is 9808. What are those page numbers?

9808 has to be equal to the sum of some consecutive natural numbers (even number of number as each page has two sides and hence two page numbers).

So,

9808 = m(m+1)/2 - n(n+1)/2

19616 = m(m+1) - n(n+1)

19616 = m^2-n^2 +m-n

= (m+n)(m-n) + m-n

= (m-n) (m+n+1)

just cant figure out how to solve this ...