Bottom Line: If your students are fluent with math facts and looking for another challenge, Math Kingdom for Kids might be a perfect fit! With 30 levels of speed-timed problem solving, develop faster skills with applying math facts. Start with 2-digit addition and work up to problems with mixed operations- for just $.99 with no ads. It does move very quickly, and there are some missing features that could move it up a star or two. Overall, it's a decent app for math facts and problem solving, and good for all ages!