According to your answer, it looks like you could use some help with geometry. We recommend starting with Volume 4 of the Learn Math Fast System. You'll learn how to find the volume, area, perimeter, and/or circumference of many shapes. Plus a lot more geometry.
RESULTS: The End of the 8th Grade Level, however, the Learn Math Fast System is for all ages. Volume 4 covers 3rd - 8th grade geometry topics, but there is no mention of grade level within the books.