Dongfeng Primary School donated 921 books to children in mountainous areas, including 254 story books, 187 comic books, and the rest are science and technology books. How many science and technology books are there?
东风小学为山区小朋友捐赠图书921本，其中故事书有254本，连环画有187本，其余的是科技书，科技书有多少本？
<gadget id="calculator">921 - 254 - 187</gadget>
<output>480</output>

<result>480</result>