How do we count various goods and services? What precautions should be taken while counting goods and services?

The task of counting enormous goods produced is tedious and cumbersome.So, the economists suggested that the value of goods and services produced should be used rather than adding the actual numbers.

The precaution that has to be taken while counting goods and services is that only final value of the goods and services should be counted, as it includes the value of all the intermediate goods that has been used wile producing the final product.