The school bought 810 workbooks, 168 for the first grade and 165 for the second grade, how many are left?
学校买来810本练习册，一年级领走168本，二年级领走165本，还剩多少本？
<gadget id="calculator">810 - 168 - 165</gadget>
<output>477</output>

<result>477</result>