You’re invited to check out out all the different learning resources in the guide: problems and projects, former Google interview questions, online courses, education sites, videos, and more. You can search for your favorite topics.
Introduction to Mathematical Thinking, Stanford University
Looking to improve your analytical skills for professional reasons? Contemplating a math-related major? You’ll learn to develop logical reasoning and increase your knowledge of discrete math in this general course designed to help you think like a mathematician. (paywall)Open link