This relationship is referred to as a stopping criterion. If it is satisfied, our result is assumed to be within
the prespecified acceptable level εs. Note that for the remainder of this text, we almost always employ absolute
values when using relative errors.
It is also convenient to relate these errors to the number of significant figures in the approximation. It can
be shown (Scarborough, 1966) that if the following criterion is met, we can be assured that the result is correct to
at least n significant figures.
εs = (0.5x10
2-n
)% (4.7)