Question: User: 555\div10
1. **State the problem:** Calculate $555 \div 10$ mentally.
2. **Understand the division:** Dividing by $10$ means moving the decimal point one place to the left.
3. **Apply the rule:** $555$ can be written as $555.0$.
4. **Move the decimal point:** Moving it one place left gives $55.5$.
5. **Final answer:** $555 \div 10 = 55.5$.
This method works for any number divided by $10$, just shift the decimal point one place left.