\[\left| \frac{1}{7} - 0,143 \right| = \left| \frac{1}{7} - \frac{143}{1000} \right| =\]
\[= \left| \frac{1000 - 1001}{7000} \right| = \left| \frac{- 1}{7000} \right| =\]
\[= \frac{1}{7000}\]