I explained the mathematics behind it. See my answer.

edit the editorial

its confusing

sum [over B=1 to P] number of multiples of B less than N+1 != The sequence ⌊ P/i ⌋ has at most 2 * √P distinct values.

correction should be here at end of following line

sum [over B=1 to P] number of multiples of B less than P+1

@darkshadows Sir, in worst case scenario, time taken by each test file will be O(T * N * N) but not O(N * N). T * N * N = 312500000 (> 3 * 10^8). Even if we consider that 10^8 instructions execute in 1 sec (which may not be the case), the solution in the editorial will give tle. Do correct me if i am wrong. Also please update the editorial with another solution if I am correct. Thanks!

sadly the constrains were so low that pre-computing values was possible… D:

Does that suppose we must not use brute force ever ?!