Final answer:
Agatha Christie wrote approximately 66 detective novels, including Murder on the Orient Express and And Then There Were None.
Step-by-step explanation:
Agatha Christie, the renowned British author, wrote approximately 66 detective novels throughout her prolific career. Some of her most famous works include Murder on the Orient Express, And Then There Were None, and The Murder of Roger Ackroyd.
Christie's detective novels continue to captivate readers with their intricate plots, memorable characters, and surprising twists.