The Dow Jones Industrial Average (DJIA) is computed by:
adding the prices of 30 large "blue-chip" stocks and dividing by 30.
calculating the total market value of the 30 firms in the index and dividing by 30.
adding the prices of the 30 stocks in the index and dividing by a divisor.
adding the prices of the 500 stocks in the index and dividing by a divisor.
adding the prices of the 30 stocks in the index and dividing by the value of these stocks as of some base data period.