The $2021^{st}$ digit at the right of the decimal point in the decimal expression of $\dfrac{6}{7}$ is~\uline{~~~~~~~~~~}~. 
Overseas Competition->Knowledge Point->Calculation Modules->Decimals->Basic Understanding of Decimals
$$\frac{6}{7}=0.\overline{857142}$$, it is a decimal which repeats in cycles of $6$ digits. Every $6$$^{th}$ digit goes back to $2$. The $2022$$$^{nd}$$ digit is $2$, so the $2021$$^{st}$ digit is $4$. 