Find closest multiple of $225$ to $873$. We see that $3 \times 225 = 675$ is the nearest. Now subtract $675$ from $873$ to get reminder $198$. Add $3$ to quotient.
Since $198$ is less than $225$, stop the division. The reminder is $198$. The topmost line $003$ is the quotient. Remove all zeros at the start of the quotient to get the actual quotient $3$.