The students showed love for the children in the disaster area, prepared 15 packs of extracurricular reading materials, 240 books in each pack, and gave 1,800 books to the No. 1 Primary School, and the rest to the No. 2 Primary School. How many books were given to the No. 2 Primary School?
同学们为灾区小朋友献爱心，准备了15包课外读物，每包240本，送给第一小学1800本，其余的送给第二小学，送给第二小学多少本？
<gadget id="calculator">240 * 15</gadget>
<output>3_600</output>

<gadget id="calculator">3_600 - 1_800</gadget>
<output>1_800</output>

<result>1_800</result>