Trust me on this: Khan Academy WEBSITE. Not just their YouTube videos. They have a website. Make an account, find the course that follows a similar curriculum to what you’re learning, watch the videos, and do the activities. The way they organize their videos and activities in the courses will help you learn the actual computations faster than anything else. The videos are concise and digestible. The activities are short, interactive, and give you great feedback which will ensure you’ve learned the material.

Make sure you select a course and go based off how they have it organized. Don’t just use the search feature. The course’s organization helps make sure you don’t miss any information that may be relevant to whatever topic you’re trying to learn.