7. (5 points) In a division equation, the dividend is 12, and the divisor is a natural number less than 12. The sum of all possible different remainders is $\qquad$ .


【Solution】Solution: Since $1,2,3,4,6$ are factors of 12, the remainder is 0,
$$
\begin{array}{l}
12 \div 5=2 \cdots 2 \\
12 \div 7=1 \cdots 5 \\
12 \div 8=1 \cdots 4 \\
12 \div 9=1 \cdots 3 \\
12 \div 10=1 \cdots 2 \\
12 \div 11=1 \cdots 1
\end{array}
$$

The sum of different remainders is $5+4+3+2+1=15$. Therefore, the answer is: 15.