This is the episode where the group defeat Myotismon, if you don't remember the episode names. Watch the episode, and look at the part where they are about to battle Myotismon. Joe and TK give Kari her Crest of Light, and Matt, Sora and Mimi all shout in surprise,"Kari's the eighth child?!" Hold on. If you remember the previous few episodes, Matt and Sora know that Gatomon is Kari's Digimon and that Kari is the eighth child. They shouldn't have been so surprised.