mot dan vit troi dng bay gap mot con vit troi bay bay theo chieu nguoc lai . con vit nay cat tieng chao mot tram ban a . con vit troi dau dan lien tiep ;ban nham roi chung toi khong phai 100 ma chung toi them chung toi them 1/2 chung toi , them 1/4 chung toi va them ban nua thi chung ta moi day 100. hoi dan vit troi co bao nhieu con
Dan vit co 36 con,bai nay co trong 400 bai toan lop 5,minh lam roi,co giao bao 36 con la dung