Find closest multiple of $1000$ to $6664$. We see that $6 \times 1000 = 6000$ is the nearest. Now subtract $6000$ from $6664$ to get reminder $664$. Add $6$ to quotient.
Since $664$ is less than $1000$, stop the division. The reminder is $664$. The topmost line $0006$ is the quotient. Remove all zeros at the start of the quotient to get the actual quotient $6$.