Many such economies of scale - including being able to buy food or cleaning materials in bigger quantities - are available to larger households. Rough and ready methods must therefore be used, of which the most common is the 'modified OECD equivalence scale' by which the first adult in each household is counted as 1.0, the second adult as 0.5, and each child under the age of 14 as 0.3. The total then becomes the number of 'equivalent individuals' by which household income must be divided.