Thinking about the current storage capacity of my card index collection, I made a back-of-the-index-card calculation:  

172,000 index cards * 150 words / card [average maximum, using front only] * 1,200 bytes / 150 words [rough average with Unicode encoding] * 1 kb / 1024 bytes * 1MB/1024 kb = approximately 200 MB of text storage

Having it well organized and indexed… Priceless.

A bright room with a green steel table on top of which sits a 1950 gray Royal KMG typewriter, a two drawer Shaw-Walker oak card index and some papers and mathematics textbooks. Behind the table is a barrister's bookcase full of books, and two card index filing cabinets.