Find closest multiple of $19999$ to $24000$. We see that $1 \times 19999 = 19999$ is the nearest. Now subtract $19999$ from $24000$ to get reminder $4001$. Add $1$ to quotient.
Find closest multiple of $19999$ to $40010$. We see that $2 \times 19999 = 39998$ is the nearest. Now subtract $39998$ from $40010$ to get reminder $12$. Add $2$ to quotient.
Since $12$ is less than $19999$, stop the division. The reminder is $12$. The topmost line $000012$ is the quotient. Remove all zeros at the start of the quotient to get the actual quotient $12$.