Housing Arithmetic for the New York Times

Okay boys and girls, today's lesson is in arithmetic. Arithmetic is very important if we want to do economics. If we don't know arithmetic, then we won't be able to notice $10 trillion stock bubbles or $8 trillion housing bubbles. That could lead to really bad mistakes in economic policy.

Today's lesson in arithmetic is necessary because the NYT told us in an article on President Obama's latest program to help underwater homeowners:

"Mr. Ballew [the chief economist at Nationwide Insurance...