On Mental Math: 1)Random difficulty jumps from test to test are enormous. Simple random choice of equation type and some of its contents aren`t working here! My suggestion, of cource, is to expand number of eq types: I got hundreds of divisions by 9,10,11 and 12, but never 13, ... Probably because these are much harder in base 10, so next obvious suggestion - assign "difficulty" to each type, by averaging times to solve it and in test, keep fixed difficulty sum for every 5-8 successive eq. Also to check if all eq within one type are the same difficulty, you may gather additional info about dispersion and divide types with highest dispersion. 2)It is incredibly unsatisfying, when eq switches when you almost solved it! Why do auto-switch? To prevent fast skipping techniques probably.. But you can just allow skip by Enter after 10 sec! Personal opinion: I am beginner mathematician and hardly get past 30 on easy. It seems I am complete FUCKING RETaRDED garbage I FUCKING HATE ALL OFF YOU!! FUCKING SITE! ill go cut my fucking throat

A. Idiot