Good Riddles

Question: Marie's father has 5 children: Nana, Nene, Nini, and Nono. Who's the 5th child?

Question: If a man has 10 birds and he sells them for 80 chicks each, how many chicks does he have?

Question: I can be shared by many or spread to few, I am as fragile as silk yet as strong as steel. Wars have been fought in my name, generations defined by me. What am I?

Question: A farmer has 10 cows, all but six die. How many are left?

Question: Disgusting and small, we wriggle through your halls, devouring books, cloths and walls. Alone we are feeble, together we have some might, glinting in our damp holes at night. What are we?