Read the passage and answer the questions.

Thomas A. Edison was born in Milan, Ohio, on February 11th, 1847. His family moved to Port Huron, Michigan, when he was seven years old. Surprisingly, he attended school for only two months. His mother, a former teacher, taught him a few things, but Thomas was mostly self-educated. His natural curiosity led him to start experimenting at a young age.

Thomas Alve Edison lit up the world with his invention of the electric light. Although the electric light seems to be the most useful, it was not his only invention. He also invented the record player, the motion picture camera, and over 1,200 other things. About every two weeks he created something new.

He worked 16 out of every 24 hours. Sometimes he worked so intensely that his wife had reminded him to sleep and eat.

Thomas Edison died at the age of 84 on October 18th, 1931, at his estate in West Orange, New Jersey. He left numerous inventions that improved the quality of life all over the world.

Question: How old was Edison when he died?