If an integer n is to be selected at random from 1…

If an integer n is to be selected at random from 1 to 900, inclusive, what is probability n(n+1) will be divisible by 9?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #31666