Xinxing Printing Factory printed a total of 2.45 million volumes of various books in April. Among them, 1.27 million copies of science and technology books were printed, 730,000 copies of magazines were printed, and the rest were books for students. How many thousands of copies of student books have been printed?
新星印刷厂4月份印各种图书共245万册．其中科技书印了127万册，杂志类印了73万册，其余是学生用书．学生用书印了多少万册？
<gadget id="calculator">245 - 127 - 73</gadget>
<output>45</output>

<result>45</result>