Trust Ben Franklin

A WSJ blog asks:

Got a $100 bill in your pocket? Chances are, you’ll spend it more slowly than you would spend five $20 bills...

research found that people spend less when carrying large bills. In short, you’re less likely to spend one $20 bill than you are to spend 20 one-dollar bills. It’s the "pain of paying", they write.

...Once you do break a big bill, things go downhill fast. Researchers found those who broke big bills tended to spend more of that money than people using smaller bills. Dr. Srivastava’s team calls this the "what the hell" effect.

"With a credit card, you don’t see cash flow visibly happening before your eyes," Prof. Srivastava says. "When you have a $100 bill, you want to save it."

Researchers got the same results in parallel studies conducted in India and China... In the U.S., 63% of all consumer transactions last year were made with some form of electronic payments.

http://blogs.wsj.com/wallet/2009/03/18/carrying-bigger-bills-youre-less-likely-to-spend-them-research-finds/