Basically you know that they are 2 consecutive numbers whose product is 1980.
n*(n+1)=1980
n^2 + n - 1980 = 0
(n -44)(n + 45)= 0
n=44
so the 2 page numbers is 44 and 45.
The faster way is just to take the square root of 1980 and since that is 44.497 you can conclude that the 2 numbers is below and above it (44, 45)
