Find closest multiple of $100$ to $304$. We see that $3 \times 100 = 300$ is the nearest. Now subtract $300$ from $304$ to get reminder $4$. Add $3$ to quotient.
Since $4$ is less than $100$, stop the division. The reminder is $4$. The topmost line $003$ is the quotient. Remove all zeros at the start of the quotient to get the actual quotient $3$.