Question 4
Let $(a_1,b_1),\ldots,(a_{100},b_{100})$ be distinct ordered pairs of nonnegative integers. Let $N$ count pairs $1\le i\lt j\le100$ for which $|a_ib_j-a_jb_i|=1$. Determine the largest possible value of $N$.
Proposed by Ankan Bhattacharya. Source: Evan Chen’s third-party solution notes.
Source video link: https://youtu.be/r7j0oRtpErA?t=4530
Proposed by Ankan Bhattacharya. Source: Evan Chen’s third-party solution notes.
Source video link: https://youtu.be/r7j0oRtpErA?t=4530