1. **Stating the problem:** We want to understand how to divide a 3-digit number by another number. 2. **Formula and rules:** Division is the process of splitting a number into equal parts. If we have a 3-digit number $N$ and want to divide it by a number $d$, the division is written as $$N \div d = q$$ where $q$ is the quotient. 3. **Step-by-step example:** Suppose we want to divide 345 by 5. 4. **Divide the hundreds place:** 3 hundreds divided by 5 is 0 (since 3 < 5), so we look at the first two digits 34. 5. **Divide 34 by 5:** 5 goes into 34 six times because $5 \times 6 = 30$. 6. **Subtract and bring down:** Subtract 30 from 34 to get 4, then bring down the next digit 5 to make 45. 7. **Divide 45 by 5:** 5 goes into 45 nine times because $5 \times 9 = 45$. 8. **Subtract:** Subtract 45 from 45 to get 0, so the division ends here. 9. **Final answer:** The quotient is 69, so $$345 \div 5 = 69$$. This method is called long division and works for any 3-digit number divided by any number.