Grandpa takes Lili to the library to buy a set of fairy tale books, 8.50 yuan each, 8 books in total. If you use the money to buy fairy tale books to buy science and technology books at 13.60 yuan each, how many books can you buy?
爷爷带丽丽到图书馆买一套童话故事书，每本8.50元，共8本．如果用买童话故事书的钱买每本是13.60元的科技书，可以买几本？
<gadget id="calculator">8 / 13.6</gadget>
<output>0.588235</output>

<gadget id="calculator">8.5 * 0.588235</gadget>
<output>4.999997</output>

<result>4.999997</result>