Reciprocal of 142,857/Mistake

Source Work

 * The Dictionary
 * $142,857$
 * $142,857$

Mistake

 * Because $142,857 \times 7 = 999,999$, the decimal period of $1 / 7$ is $142857$ and the decimal period of $1 / 142,857$ is $7$. In fact $1 / 142,857 = 0.000007 \, 000007 \, 000007 \, \ldots$

Careful counting reveals that the period is in fact $6$, not $7$.