A miner minesiron ore, which he sells to a blacksmith for $1,500.
The blacksmith produces steel pipes, which he sells to a plumber for $1,800.
The plumber produces all sorts of plumbing services, which are sold to the public for $2,700.
If we made the mistake of double counting at every level of production, as opposed to using the valued added approach, we would calculate the total value of the output to be $6000
If we use the valued added approach, the true value would be $2700.
This means we would have overestimated the true value of the output by 122.22%.