How much longer can the United States continue to spend more money than it takes in, and how much longer can we continue our spendthrift ways before something literally gives? The numbers are getting so big that they are beyond comprehension. For example, billions and trillions of dollars are almost impossible to understand. Generally, we seem to know what a million dollars can buy. We see the number in the prices of real estate and homes, or perhaps the statistics about various businesses. But, we rarely see big numbers illustrated in terms that are easier to visualize. For example, a...