Unknown.
Most of us ask for a printed confirmation, almost by rote, when we withdraw money from an ATM or purchase a ticket from a subway machine. More likely than not, the receipt disappears into the folds of our already-overstuffed wallets, never to encounter daylight again. Multiply that by 8 billion, which is how many ATM transactions happen each year in the United States, according to a 2006 survey (PDF), and we're practically eyebrow-deep in unnecessary waste.
Save yourself some clutter, and the planet some of its global-warming-fighting trees, simply by saying no whenever you have the option. You can review your ATM transaction at your bank's Web site, as well as keep tabs on credit-card expenses via online statements.
Difficulty level: Easy
