The school bought a batch of children's books and distributed them to 31 classes. Each class distributed 50 books, and there were 135 books left. How many children's books did the school buy in total?
学校买来一批少儿读物，发给31个班的同学，每班发50本，还剩135本．学校一共买来多少本少儿读物？
<gadget id="calculator">50 * 31</gadget>
<output>1_550</output>

<gadget id="calculator">1_550 + 135</gadget>
<output>1_685</output>

<result>1_685</result>