The school intends to set up a separate popular science library and purchased 1,500 popular science books. Now I plan to buy bookshelves. If each bookshelf has 4 layers and each layer contains 25 books, how many such bookshelves do I need to buy?
学校打算单独设立一间科普图书室，购进了1500本科普读物．现在打算购买书架，如果按每个书架4层，每层放25本书计算，需要购进多少个这样的书架？
<gadget id="calculator">25 * 4</gadget>
<output>100</output>

<gadget id="calculator">1_500 / 100</gadget>
<output>15</output>

<result>15</result>