Sage of the Arctic

Iron Maiden

The alchemist's store appears empty, and Jeremiah walks in, following the scraping sounds of metal on metal. Covered in grime, the alchemist is hunched over a pile of rusty nails and filing away at the ends of old aluminum cans. "Jeremiah, grab a can, start filing. I have 3.8891 kilograms of rusty nail, but only 0.4464 kilograms of powdered aluminum."

"Mr. Alchemist, sir, this seems to be a lot of work. Why don't you try your experiment now, and save the leftover materials?"

"Actually... that's a really good idea. How many moles of rust will I have left if I use up all of the aluminum?