>>11947890>>11953866Expii.com which is owned by this guy the US math olympiad coach:
https://www.poshenloh.com/ expii is free and you can just drill yourself problems
He also has this daily challenge thing
https://daily.poshenloh.com/ which is a pretty good idea, everyday for a month you work 1hr on various math problems with him giving a full recorded solution on it. it's pretty good, sadly the paid modules are too expensive, $150USD but see the free module examples maybe make your own daily challenge