The $1985^{}\text{th}$ digit at the right of the decimal point in the decimal expression of $\dfrac{1}{7}$ is~\uline{~~~~~~~~~~}~. 
Overseas Competition->Knowledge Point->Calculation Modules->Decimals->Basic Understanding of Decimals
$$\frac{1}{7}=0.\overline{142857}$$, it is a decimal which repeats in cycles of $6$ digits. Every $6$\textsuperscript{th}~digit is $7$. The $1986$\textsuperscript{th} digit is $7$, so the $1985$\textsuperscript{th} digit is $5$. 