A few days ago, as I was delving into the mess in my grand parents' attic, I found an impressive ancient book that was written in a language that I had never seen before.
"This book is a collection of riddles printed in the eighteenth century." Grandma said. "One in particular is worth reading: it is said to be the ancestor of the age-of-the-captain riddles. Let me translate it to you."
And she proceeded:
A Captain's son asks his father:
"Why Father, I've noticed that we never celebrate your birthday, and in fact I don't think I even know when you were born."
Answers the Captain:
"If you subtract four from the day I was born, then you get a non-zero integer with at least two distinct prime divisors, one of which is the month I was born. Now with that knowledge, if I tell you the day I was born, then you shall know the year as well."
What was the Captain's date of birth? (dd/mm/yyyy)
She then closed the book and stared into my eyes with the most mischievous look I'd ever seen. She asked:
"In what language was this book written?"