Finding price-to-earnings ratios for the stock market isn't hard

— -- Q: Is there a place where I can find the price-to-earnings ratio of the Dow Jones industrial average?

A: Investors commonly determine if a stock is cheap or expensive by looking at its price-to-earnings ratio (P-E).

Punch SPY into any Get a Quote box at money.usatoday.com. You'll get a complete data sheet. If you scroll down, you'll see the P-E ratio of SPY recently was around 14, relatively low by historical standards, except for the period from 1977-82.

You can find a link to the historical P-E ratio for the S&P on this page.

You can do the same for the Dow Jones industrial average. Calculating the Dow's P-E by hand requires quite a bit of effort.

Punch DIA into any Get a Quote box at money.usatoday.com. You'll get a complete data sheet.

If you scroll down, you'll the P-E on the Diamonds ETF. This is a good benchmark for the P-E on the Dow.

Matt Krantz is a financial markets reporter at USA TODAY and author of Investing Online for Dummies. He answers a different reader question every weekday in his Ask Matt column at money.usatoday.com. To submit a question, e-mail Matt at mkrantz@usatoday.com. Click here to see previous Ask Matt columns.