11. (9 points) With 70 yuan, four types of books, Jia, Yi, Bing, and Ding, were bought, totaling 10 volumes. It is known that the prices of Jia, Yi, Bing, and Ding books are 3 yuan, 5 yuan, 7 yuan, and 11 yuan per book, respectively, and at least one book of each type was purchased. How many different ways of purchasing are there? $\qquad$
【Solution】Solution: $3+5+7+11=26$ (yuan),
$$
\begin{array}{l}
70-26=44 \text { (yuan), } \\
10-4=6 \text { (books), }
\end{array}
$$

Therefore, 44 yuan is used to buy 6 books,
(1) Buy 1 book priced at 11 yuan, 4 books priced at 7 yuan, and 1 book priced at 5 yuan,
$$
11 \times 1+7 \times 4+5 \times 1=44 \text { (yuan) } \text {, }
$$
(2) Buy 2 books priced at 11 yuan, 1 book priced at 7 yuan, and 3 books priced at 5 yuan,
$$
11 \times 2+7 \times 1+5 \times 3=44 \text { (yuan), }
$$
(3) Buy 2 books priced at 11 yuan, 2 books priced at 7 yuan, 1 book priced at 5 yuan, and 1 book priced at 3 yuan,
$$
11 \times 2+7 \times 2+5 \times 1+3 \times 1=44 \text { (yuan), }
$$
(4) Buy 3 books priced at 11 yuan, 2 books priced at 3 yuan, and 1 book priced at 5 yuan,
$$
11 \times 3+3 \times 2+5 \times 1=44 \text { (yuan), }
$$

There are 4 ways in total,
The answer is: 4.