1. (5 points) $111 \div 3+222 \div 6+333 \div 9=$
【Analysis】According to the law of the invariance of quotient, we can get $111 \div 3+111 \div 3+111 \div 3=111 \times 3 \div 3$. By calculating according to this, we can find the solution.
【Solution】Solution: $111 \div 3+222 \div 6+333 \div 9$
$$
\begin{array}{l}
=111 \div 3+111 \div 3+111 \div 3 \\
=111 \times 3 \div 3 \\
=111 .
\end{array}
$$

The answer is: 111.
【Comment】This problem examines the clever calculation in four mixed operations, the key is to flexibly apply the law of the invariance of quotient.