This is a training book for 4th graders to strengthen their basic math skills using the SAPIX method. With answer key and explanations. [Unused] I've checked it over briefly, but please forgive any missing pages or scribbles. Please excuse any minor stains or scribbles as it was stored at home. Please refrain from purchasing if you are overly concerned about condition. As this item is subject to being copied, returns are not accepted after purchase. Thank you for looking.