Try ALEKS. It's basically an online grind session that identifies which underlying concepts you've got wrong or haven't got, and builds you toward them organic

Try ALEKS. It's basically an online grind session that identifies which underlying concepts you've got wrong or haven't got, and builds you toward them organically. I recently used it to get myself sufficiently intimate with trigonometry that I don't have to stop and look things up all the time "just in case." It's not free but it works well: https://www.aleks.com https://www.aleks.com