11. (3 points) Among the 100 natural numbers from 1 to 100, the sum of all numbers that cannot be divided by 6 is
【Solution】Solution: $(1+100) \times 100 \div 2-6 \times(1+2+3+\cdots+16)$,
$$
\begin{array}{l}
=5050-6 \times(1+16) \times 16 \div 2, \\
=5050-816, \\
=4234 ;
\end{array}
$$

The answer is: 4234 .