Find closest multiple of $12$ to $21$. We see that $1 \times 12 = 12$ is the nearest. Now subtract $12$ from $21$ to get reminder $9$. Add $1$ to quotient.
Since $9$ is less than $12$, stop the division. The reminder is $9$. The topmost line $01$ is the quotient. Remove all zeros at the start of the quotient to get the actual quotient $1$.
