Find closest multiple of $12$ to $25$. We see that $2 \times 12 = 24$ is the nearest. Now subtract $24$ from $25$ to get reminder $1$. Add $2$ to quotient.
Find closest multiple of $12$ to $17$. We see that $1 \times 12 = 12$ is the nearest. Now subtract $12$ from $17$ to get reminder $5$. Add $1$ to quotient.
Since $5$ is less than $12$, stop the division. The reminder is $5$. The topmost line $021$ is the quotient. Remove all zeros at the start of the quotient to get the actual quotient $21$.
