Accuracy

Approximations are also unavoidable in calculations. Neither people nor computers can provide a totally accurate number for 1/3 or pi or any of several other numbers, and often the desired accuracy does not require it. The person calculating does, however make sure that the approximations are sufficiently small that they do not endanger the useful accuracy of the result. Accuracy becomes an issue in computations because rounding errors accumulate, series expansions are attenuated, and other methods that are not analytical tend to include errors.