Some online resources that can help with math questions and math homework include PurpleMath, MathIsFun and Khan Academy. These sites all offer student-friendly explanations and examples for common math concepts from the Kindergarten level all the way up through calculus.
Mathisfun focuses primarily on elementary math through algebra and breaks concepts down into small pieces that are easy to digest for younger students. The site focuses on relating math concepts to the real world and also offers games and puzzles designed to integrate and solidify the concepts.
PurpleMath is more focused on upper-level math, but it does also cover concepts as low as 5th grade. The site features interactive examples and specializes in helping students learn how to navigate more complicated problems. It provides commonly used formulas and equations and also has a forum where users can post specific homework questions and get help on how to solve them.
Khan Academy is an online learning resource that provides students with help learning and reinforcing concepts in several subjects in addition to math. Creating an account on the site is free and allows users to track progress or work on specific concepts or goals. The site features a multimodal learning platform that includes text, videos and interactive examples.