Where the shape comes from
Two figures 匕 standing one behind the other, facing the same way and matched shoulder to shoulder — set two things side by side and you can see which is greater. Turn the same pair back to back and you get 北. It is the character behind the everyday comparison 我比你高 and behind 比较, and it lends its sound to 批 and 毕.
汉字 filed under 比
No published character on HSK Guide is filed under this radical yet. 汉字库.